PROSPECTING,  LOCATING 


AND 


VALUING 


A  Practical  Treatise  for  the  use  of  Prospectors,  Investors  and  Mining  Men. 

generally;  with  an  account  of  the  Principal  Minerals  and  Country  Rocks; 

Ore  Deposits;  Locations  and  Patents;  the  Early  Development 

of  Mines;  Earthy  Mineral  Products;  Coal;  Gold  Gravels 

and  Gravel  Mining;  Measurement  of  Water; 

and  Artesian  Wells. 


WITH  FIFTEEN  PLATES. 


BY 

R*  R  STRETCH,  E.M* 


SECOND  EDITION. 


THE  SCIENTIFIC  PUBLISHING  COMPANY: 

NEW  YORK  AND  LONDON. 
1900. 

206  BOSTON  BUILDING^ 
DENVER,  COLO. 


COPYRIGHT,  1899, 

BY 
THE  SCIENTIFIC  PUBLISHING  COMPANY 


CONTENTS. 


I.  Introductory —Mistakes  in  Mining.  ....... 1 

II.  What  Constitutes  a  Mine . . .  r «, 16 

III.  Rock-forming  Minerals  and  Rocks 3 . . . .  t 36 

IV.  Physical  Character  of  Mineral  Deposits 69 

V.   Origin  of  Veins , 0 .  „  „ 83 

VI.   Filling  of  Mineral  Veins 4    . . ,     99 

VII.  Influence  of  Rocks  on  Vein  Filling , . ,   120 

VIII.  Mineral  Deposits  Other  than  Veins . . ,   138 

IX.  Prospecting . . .  . a .  150 

X.  Making  Locations 0 ;>."•«   167 

XI.   Patents  to  Mining  Ground 187 

XII.  Early  Development  of  Mines. .  * 197 

XIII.  Ores .. ... 206 

XIV,  Useful  Earthy  Minerals,  etc 229 

XV.  Coal ,.,o 259 

XVI.  Gold  Gravel  Deposits 271 

XVII.  Water  and  Its  Measurement 302 

XVIII.  Artesian  Wells 310 

Useful  Tables 316 

Good  Books  of  Reference.. 338 

Plates  1  to  15  inclusive. , 344 

Index...  .  374 


438579 


PROSPECTING,  LOCATING 

..AND.. 

VALUING  MINES. 


CHAPTEK  I. 
INTRODUCTORY— MISTAKES  IN  MINING. 

THE  following  pages  are  not  intended  for  those  who 
have  devoted  a  lifetime  to  mining  and  are  educated  in 
the  many  branches  of  knowledge  which  go  to  make  the 
successful  mining  man,  but  for  those  who  would  like  to 
invest  a  portion  of  their  capital  in  the  business  if  they 
felt  safe  in  so  doing,  and  who  hold  back  because  of 
their  complete  ignorance  of  the  subject ;  and  to  restrain 
the  over-sanguine  temperaments  of  others,  by  pointing 
out  the  elements  which  may  militate  against  success. 
At  the  same  time  it  is  believed  that  the  prospector  will 
also  find  hints  which  will  assist  him  in  his  \\  ^arisome 
labors,  enable  him  to  ma*ke  his  locations  to  better  ad- 
vantage than  is  now  the  case  in  a  very  large  proportion 
of  those  on  record,  and  furnish  him  with  the  language 
in  which  he  can  intelligently  describe  to  others  what 
he  has  found,  so  that  they  shall  see  it  just  as  he  does, 
and  be  able  to  verify  his  statements  upon  inspection. 

It  is  hoped  that  the  explanations  and  suggestions 
will,  to  some  extent  at  least,  prevent  him  from  spend- 
ing time  and  money  on  valueless  prospects  or  worthless 
minerals;  furnish  him  with  the  means  to  determine 
approximately  the  value  of  what  he  has  found,  and 


2  PROSPECTING  AND   VALUING  MINES. 

show  him  the  way  to  develop  it  at  the  least  expendi- 
ture of  time  and  labor;  and  enable  him  to  see  clearly 
what  nature  has  done  to  his  advantage,  or  the  obstacles 
which  have  been  thrown  in  his  way. 

It  is  not  pretended  that  new  geological  facts  have 
been  presented.  Nearly  all  of  them  can  be  found  in 
the  books,  but  they  are  scattered  through  many  and 
often  expensive  works,  and  in  but  few  cases  is  there 
any  allusion  to  the  practical  bearing  of  these  facts  on 
the  interests  of  the  miner,  except  in  the  case  of  coal 
mining,  which  has  a  complete  and  extensive  literature 
of  its  own.  In  all  these  works,  geology,  in  its  relation 
to  coal  mining,  receives  full  attention,  but  it  has  been 
otherwise  with  vein  mining  for  the  precious  metals. 
Where  it  would  be  impossible  to  put  the  subject  matter 
into  better  language,  the  writer  has  quoted  freely  from 
recognized  authorities,  and  has  used  some  illustrations 
which  may  almost  be  called  common  property  from 
the  frequency  with  which  they  have  been  copied  by 
one  writer  after  another;  but  a  large  proportion  of  the 
illustrations  are  drawn  from  the  writer's  own  note- 
books. 

The  object  of  the  book  may  be  best  illustrated  by 
a  few  words  on  the  causes  of  failure  of  mining  enter- 
prises which  it  is  sought  to  avoid  by  calling  special 
attention  thereto.  In  mercantile  business,  failures 
arise  from  undue  competition,  depression  in  trade, 
wrong  selection  of  location,*  want  of  capital,  lack  of 
business  tact,  want  of  knowledge  of  the  trade,  etc.  In 
gold  mining,  and  to  a  certain  extent  in  silver  mining, 
we  get  rid  of  the  element  of  competition ;  and  in  gold 
mining,  at  least,  depression  in  trade  does  not  affect 
otherwise  than  as  a  stimulus,  but  ail  other  causes 
operate  in  very  much  the  same  manner  both  in  mining 
and  trade. 

It  should  be  kept  in  mind  that  every  pound  of  ore 
taken  from  a  mine  leaves  just  that  much  less  in  it,  and 
that  the  end  must  inevitably  come  at  some  time.  In 


INTRODUCTORY.  3 

this  respect  a  mine  differs  essentially  from  a  mercan- 
tile business  which  can  enlarge  its  field  of  operations 
year  after  year  as  population  increases  or  facilities  of 
communication  are  improved.  If  the  mine  only  yields, 
above  working  expenses,  a  sum  sufficient  to  repay  the 
cost  of  the  ground,  development  and  plant,  the  investor 
might  just  as  well  have  buried  his  dollars  for  the  same 
period  of  time,  and  saved  labor  and  mental  strain. 
This  state  of  affairs  may  easily  occur  even  when  the 
mine  has  rich  ore  in  sight. 

It  takes  just  as  deep  a  shaft  to  open  a  piece  of 
ground  500  ft.  long  as  if  it  were  2,000,  but  the  cost  of 
sinking  and  pumping,  and  all  expenses  of  corporate 
management  will  be  four  times  as  great  per  square 
foot  of  area  developed  in  one  case  as  in  the  other,  and 
this  difference  may  do  away  with  the  possibility  of 
dividends  or  even  the  recovery  of  the  invested  capital. 

Numerous  cases  of  this  kind  have  been  seen  in  Colo- 
rado and  elsewhere,  where  small  properties  which 
could  not  stand  the  burdens  thus  imposed  upon  them 
have  proved  successful  when  consolidated,  one  shaft 
answering  for  a  much  larger  property,  thus  saving  the 
cost  of  constant  sinking,  the  expense  of  numerous 
engines  and  surface  hands,  as  well  as  superintendence 
and  office  expenses. 

On  the  other  hand  an  enterprise  may  have  so  much 
ground  that  the  energies  of  the  company  are  scattered 
over  too  large  an  area,  one  unproductive  section  eat- 
ing up  the  profits  of  the  better  ground,  thus  leading 
to  constant  embarrassment;  and  a  failure  under  these 
circumstances  may  do  as  much  to  blast  the  reputation 
of  a  district  as  if  the  property  had  been  absolutely 
barren  throughout. 

This  condition  of  the  mine  as  regards  its  capital 
renders  it  undesirable,  if  not  dangerous,  to  experiment 
with  new  processes  of  reduction.  So  many  of  these, 
while  eminently  successful  in  the  laboratory,  when 
worked  on  a  small  scale  and  by  enthusiasts  thoroughly 


4  PROSPECTING  AND   VALUING  MINES. 

posted  on  all  the  minute  details,  have  proved  so  inap- 
plicable on  a  large  scale,  when  operated  by  less  careful 
men,  that  a  mine  cannot  afford  to  employ  them  until 
they  have  proved  entirely  satisfactory  under  all  similar 
working  conditions.  The  cost  of  the  experiments 
should  be  borne  by  the  projectors  of  the  innovations; 
all  that  a  mine  dare  do  is  to  pay  a  royalty  or  purchase 
the  machinery  when  it  is  no  longer  an  experiment. 
It  is  true  that  the  improved  machinery,  so  called, 
might  be  a  real  improvement  and  a  desirable  acquisi- 
tion, but  on  the  other  hand,  if  a  failure,  it  would  be 
only  another  tax  on  a  treasury  which  has  already  its 
full  share  of  burdens. 

Again,  the  price  given  for  a  mine  may  be  so  exorbi- 
tant, or  out  of  proportion  to  its  development,  that 
while  it  may  pay  dividends  for  a  time  and  apparently 
be  a  success,  the  ore  body  may  "peter  out"  before  the 
purchase  price  has  been  returned  in  the  shape  of  divi- 
dends; and  failure  will  ensue,  unless  a  reserve  fund 
has  been  set  aside,  with  which  to  search  for  other  ore 
bodies,  The  disproportionate  profits  of  the  middlemen 
or  promoters  emphasize  this  proposition,  as  in  the 
case  of  the  Kichmond  Consolidated  mine  in  Nevada> 
which  is  said  to  have  cost  the  stockholders  $1,375,000 
while  the  vendors  received  about  $280,000,  leaving 
the  promoters  a  clean  profit  of  over  a  million  dollars. 
Luckily  the  mine  repaid  this  enormous  purchase  price, 
but  had  it  nut,  it  would  have  been  condemned  as  a 
failure,  when  it  was  not  legitimately  entitled  to  be 
saddled  with  so  great  a  burden.  This  was  strictly 
gambling,  not  mining.  The  same  thing  has  happened 
in  floating  the  mines  of  many  other  districts,  and 
notably  so  in  the  case  of  the  Transvaal — usually  with 
a  less  fortunate  outcome. 

A  common  cause  of  failure  is  in  not  keeping  the 
development  of  the  mine  ahead  of  its  current 
necessities.  Such  work  will  naturally  reduce  the 
dividends  for  a  time,  but  it  is  far  preferable  to  pay 


INTRODUCTORY.  5 

for  these  developments  out  of  the  profits  of  the  mine, 
while  it  is  prosperous,  than  to  have  to  raise  an  asess- 
ment  for  the  purpose  when  it  is  looking  poor.  Those 
who  have  tried  the  latter  plan  know  the  attendant 
difficulties,  which  are  especially  conspicuous  in  the 
case  of  mines  represented  by  unassessable  stock.  To 
such  mines  an  empty  treasury  means  almost  inevi- 
table death,  although  a  little  medicine  in  the  shape  of 
coin  might  give  them  a  long  lease  of  life.  It  always 
happens  that  there  are  some  stockholders  who  will 
not  advance  any  more  capital,  and  the  rest  do  not 
feel  inclined  to  do  so  and  allow  the  non-payees  to  come 
in  and  reap  the  benefits;  while  there  is  no  way  in 
which  undesirable  partners  like  the  non-paying  stock- 
holders can  be  got  rid  of,  except  by  foreclosure  of  a 
judgment  for  an  indebtedness  of  the  property. 

Another  frequent  source  of  lost  money  is  the  erec- 
tion of  mills  or  other  reduction  works  before  they  are 
required.  Nevada  is  full  of  illustrations  of  this  kind 
of  folly,  which  is  more  apt  to  be  committed  by  com- 
panies than  by  individuals.  In  many  cases  magnifi- 
cent mills  were  erected  before  the  mine  had  been 
opened  even  sufficiently  to  know  if  there  was  a  mine 
at  all,  and  never  dropped  a  stamp.  Some  of  these  enter- 
prises were  unmitigated  swindles  and  seriously  hurt 
our  mining  interests  abroad,  so  that  the  recovery  of 
confidence  took  years  to  complete.  Not  a  few  of  these 
mills  were  also  utterly  unsuited  to  the  ore  of  the  dis- 
trict and  were  consequently  valueless  even  for  custom 
use  on  the  ore  of  other  mines.  In  other  cases  the 
mills  have  been  too  large  for  the  property  for  which 
they  were  erected,  and  it  has  been  impossible  to  keep 
them  running  steadily — to  their  injury,  as  machinery 
deteriorates  rapidly  from  idleness.  It  would  seem 
that  few  miners  have  any  idea  of  the  amount  of  ore 
which  even  a  10-stamp  mill  will  consume  in  a  year. 
We  often  hear  that  a  mine  is  ready  for  a  mill,  when  it 
has  only  a  shaft  from  50  to  100  ft.  deep,  or  a  tunnel  of 


6  PROSPECTING  AND  VALUING  MINES. 

the  same  length.  The  absurdity  of  this  proposition  is 
apparent.  There  may  of  course  be  instances  where 
the  outcrop  is  so  continuously  in  ore  that  there  can  be 
no  doubt  of  our  ability  to  put  the  mine  in  shape  for 
extraction  during  the  time  consumed  in  the  erection 
of  a  mill,  but  this  is  quite  exceptional. 

Serious  troubles  have  also  arisen  from  false  expecta- 
tions based  on  small  quantities  of  rich  ore,  or  rather  of 
narrow  seams.  If  these  could  be  taken  out  by  them- 
selves they  would  often  pay  handsomely,  even  when 
the  quantities  would  not  warrant  the  erection  of  a  mill, 
but  as  they  cannot  be  extracted  without  removing  a 
large  quantity  of  waste,  the  cost  of  doing  this  has  to 
be  taken  into  consideration,  as  well  as  the  difficulty  of 
preventing  the  loss  of  ore  by  mixture  with  the  waste, 
even  when  carefully  hand-sorted.  It  is  not  intended 
to  intimate  that  these  very  small  veins  or  seams  may 
not  be  worth  working,  for  seams  of  very  diminutive 
thickness  are  worked  at  the  mines  at  Nagyag  in  Tran- 
sylvania; and  in  some  cases,  as  the  native  silver  mines 
of  Batopilas  in  Mexico,  the  sheet  of  ore  is  so  tough 
that  when  less  than  an  inch  in  thickness  it  may  be  left 
standing  while  the  drift  is  run  alongside,  and  stripped 
down  once  a  week  or  oftener,  as  may  be  desirable.  The 
object  is  to  call  attention  to  the  frequent  excessive  cost 
of  working  very  narrow  ore  seams,  that  due  allowance 
may  be  made  and  failure  avoided. 

Want  of  knowledge  of  the  structure  of  the  deposit 
is  often  a  source  of  costly  errors.  It  is  not  many 
years  ago  that  the  writer  saw  a  summer's  work  thrown 
away  by  a  superintendent  losing  the  vein  and  not 
knowing  how  to  find  it  again.  Starting  on  the  vein 
he  apparently  mistook  the  bedding  of  the  rock  for  the 
wall,  as  shown  in  pi.  6.,  fig.  2,  and  on  reaching  the 
point  B,  where  the  ore  apparently  pinched  out,  went 
off  into  the  country  rock  along  a  small  seam  in  the 
hanging  wall  S.  Not  finding  the  large  ore  body  which 
was  known  by  its  outcrop  to  exist  ahead  of  the  tunnel, 


INTRODUCTORY.  7 

he  crosscut  in  the  wrong  direction  at  A  toward  (7, 
when  finding  another  small  seam  he  turned  back  on 
that  toward  the  main  vein  again.  Had  he  continued 
on  the  line  A  C  he  would  have  come  out  to  daylight 
in  a  direction  exactly  opposite  to  that  in  which  he 
should  have  sought  the  ore  body.  The  tunnel  was 
run  in  hard  granite  under  very  adverse  circumstances, 
entailing  a  serious  outlay  of  money,  which  must  be 
charged  against  any  future  profits,  because  whatever 
is  spent  on  a  mine  ought  to  come  out  of  it,  and  at  the 
end  of  the  season's  work  the  property  w?as  in  a  less 
satisfactory  condition  than  before  the  tunnel  was  run ; 
as  many  observers  would  naturally  come  to  the  con- 
clusion that  the  mine  was  practically  worthless,  if  the 
ore  seen  on  the  surface  was  lost  so  promptly  in  depth. 
(It  has  since  been  satisfactorily  opened  in  the  right 
direction.)  The  same  amount  of  money  properly  ex- 
pended under  judicious  management  would  have  taken 
the  tunnel  through  a  body  of  ore  which  crops  continu- 
ously for  several  hundred  feet,  and  would  have  been 
extracting  ore  for  its  entire  length,  thus  making  a 
profit  instead  of  a  loss,  and  putting  the  mine  in  shape 
for  stoping. 

A  most  astonishing  want  of  common  sense  in  read- 
ing the  lesson  of  the  outcrop  has  caused  the  loss  of 
much  time  and  money.  In  the  case  of  the  mine  shown 
in  pi.  12,  fig.  5,  the  outcrop  of  the  vein  occupied 
the  fiat  slope  of  a  valley  with  a  steep  hill  to  the  north, 
and  was  scattered  over  a  width  of  100  ft.  for  a  consid- 
erable distance,  but  was  not  continuous,  being  broken 
up  into  little  patches  of  varying  size.  The  ore  was 
rich,  and  being  stained  with  the  blue  and  green  car- 
bonates of  copper,  was  very  conspicuous  by  contrast 
with  the  underlying  yellowish  limestones.  Evidently 
this  was  mistaken  for  the  outcrop  of  an  immense  vein 
or  bed,  but  a  very  casual  examination  showed  that  the 
vein  was  only  a  thin  film  between  the  slates  S  and 
limestones  L,  for  the  little  gulches  running  north  to 


8  PROSPECTING  AND   VALUING  MINES. 

the  main  ravine  had  cut  through  the  ore  in  numerous 
places,  in  all  cases  revealing  the  underlying  limestone, 
and  showing  the  true  character  of  the  deposit.  That 
it  was  not  understood  was  proved  by  the  company 
running  the  tunnel  Tto  cut  the  vein.  This  was  started 
in  the  foot  wall  and  beneath  the  seam,  and  naturally 
never  encountered  ore.  Had  any  further  proof  been 
wanting,  nature  had  furnished  it,  for  at  the  eastern 
end  of  the  location,  the  bluffs  (overlooking  Death 
Valley,  Cal.)  broke  down  perpendicularly  for  several 
hundred  feet,  and  had  the  vein  been  other  than  it  was 
it  must  have  shown  conspicuously  on  the  face  of  these 
precipices,  which  it  did  not.  It  would  seem  that  this 
idea  had  never  occurred  to  the  purchasers,  who  were 
out  of  pocket  on  the  transaction  from  $100,000  to 
$150,000  in  purchase  money  and  working  expenses, 
while  another  mining  failure  was  talked  about  and 
nothing  said  of  the  folly  of  the  investors  and  man- 
agers, who  would  not  believe  the  facts  of  the  case  even 
when  they  had  paid  to  find  them  out. 

Again,  it  is  only  recently  that  a  man  professing  to 
be  a  mining  engineer  recommended  the  exploitation  of 
a  bed  of  bog  iron  ore,  when  a  casual  investigation 
showed  that  it  was  a  deposit  now  forming,  only  a  few 
inches  thick,  limited  to  a  few  acres  of  marshy  ground, 
and  did  not  show  a  few  hundred  feet  to  the  westward, 
where  the  ground  breaks  down  abruptly  in  a  bluff  to 
the  seashore,  consisting  entirely  of  unconsolidated 
sand  and  gravel.  Investors  in  such  a  scheme  would 
have  faced  certain  failure  from  the  start,  and  would 
unanimously  have  condemned  mining  as  a  business. 

Another  method  of  losing  money  is  to  sink  or  bore 
for  metals,  coal  or  oil,  or  any  other  substance  occur- 
ring in  beds  or  bedded  veins,  when  nature  has  told 
the  whole  story  on  the  upturned  edges  of  the  rocks, 
as  shown  in  pi.  4,  fig.  4,  and  pi.  3,  fig.  5.  In  pi.  4,  fig. 
4,  a  shaft  sunk  at  D  would  disclose  no  more  informa- 
tion than  could  be  gained  by  walking  over  the  country 


INTRODUCTORY  9 

toward  B,  when  tbe  observer  will  pass  over  all  the 
rock  strata  which  would  be  cut  in  the  shaft,  with  an 
immensely  better  opportunity  of  examining  them  in 
detail  and  without  cost.  If  there  is  anything  of  value 
shown,  as  a  coal  seam  at  B,  its  merits  can  be  discussed 
before  the  expenditure  of  a  dollar  for  underground 
workings,  and  an  incline  could  be  sunk  on  it  to  greater 
advantage  than  the  vertical  shaft  Z>,  at  least  until  a 
full  knowledge  of  its  character  had  been  obtained. 
This  mistake  has  been  repeated  so  often  that  every 
person  connected  with  mining  must  be  able  to  recall 
instances.  The  same  might  be  said  of  a  shaft  at  B,  pi. 
3,  fig.  5,  but  at  A}  in  the  same  figure,  a  shaft  would 
be  excusable.  In  the  neighborhood  of  Leadville,  Colo., 
the  writer  has  seen  a  prospector  sinking  in  the  granite 
to  find  carbonate  of  lead  ore,  which  was  an  absolutely 
hopeless  undertaking,  as  can  be  seen  by  reference  to 
the  cross  section  of  the  Leadville  district,  pi.  1,  fig.  2, 
where  the  granite  and  gneiss  underlie  everything  arid 
the  ore  is  associated  with  the  porphyry  and  limestone 
beds  above  it.  The  utter  improbability  of  success 
would  have  been  apparent  to  the  prospector  had  he 
possessed  even  a  smattering  of  knowledge  of  rocks  and 
the  occurrence  of  ore,  but  his  shaft  was  another  mem- 
ber of  the  army  of  failures  for  want  of  that  knowledge. 
To  him  the  proposition  was  plain  that  because  others 
had  sunk  shafts  and  found  ore  at  varying  depths, 
without  any  surface  showing,  he  had  just  as  good  a 
chance  as  they.  On  the  other  hand  the  want  of  the 
necessary  preliminary  exploration  by  boring,  in  the 
case  of  coal  fields  especially  (after  the  presence  of  coal 
is  known),  may  entail  loss  and  failure  owing  to  the 
breaking  up  of  the  beds  by  faults,  the  presence  of 
which  would  have  been  made  evident  by  a  proper 
series  of  borings  in  each  direction.  The  beds  might 
not  be  ' 'faulted"  or  broken  so  regularly  as  in  the 
idealized  cross  section  on  pi.  1,  fig.  1,  which  shows  a 
series  of  "step  faults,"  but  the  figure  will  illustrate 


10  PROSPECTING  AND  VALUING  MINKS. 

the  general  idea.  Let  B,  E,  F  and  H  represent  bor- 
ings. If  only  B  and  jEf  have  been  made,  the  coal  seam, 
represented  by  the  heavy  black  line,  would  have  been 
found  in  each,  and  its  dip  fairly  ascertained,  but  no 
indication  of  the  faults  A  and  B  would  have  been  de- 
tected, unless  the  bore  hole  //had  been  carried  down 
some  distance  below  the  coal,  and  the  works  for  the 
extraction  of  coal,  based  on  these  borings  alone,  might 
be  valueless  for  working  the  bed  between  the  faults  B 
and  G.  But  if  the  borings  had  been  extended  over  a 
larger  area  and  included  others  at  E and  F9  the  broken 
nature  of  the  formation  would  have  been  disclosed  and 
led  to  a  thorough  investigation  as  to  whether  the 
locality  could  be  profitably  worked,  and  if  not  the  cost 
of  permanent  works  would  have  been  avoided.  What 
has  been  said  of  coal  applies  to  many  of  the  gold 
gravel  mines  in  California  as  well. 

Even  if  the  quantity  and  quality  of  the  material, 
such  as  coal,  iron  ore,  clay  and  other  minerals,  which 
come  into  severe  competition  with  each  other,  and 
require  every  facility  in  the  way  of  cheap  labor,  cheap 
transportation,  and  an  extended  market  for  successful 
production,  be  all  that  can  be  asked,  the  deposits  may 
be  so  situated  with  regard  to  the  latter  requirements 
that  commercial  failure  must  result  from  their  explora- 
tion. Andre,  in  his  treatise  on  coal  mining,  p.  80, 
puts  the  case  very  clearly : 

"But  if  certain  clearly  apparent  circumstances  exist 
which  are  sufficient  of  themselves  to  show  that  the 
undertaking  cannot  be  commercially  successful,  even 
if  all  the  other  circumstances  should  prove  favorable, 
it  is  plain  to  ordinary  common  sense  that  it  would  be 
sheer  folly  to  prosecute  a  search  which  must  necessarily 
be  an  expensive  one,  and  which  must  as  necessarily 
end  in  disappointment.  Enormous  sums  of  money 
have  been  expended  in  this  way  to  the  great  and  mani- 
fest injury  of  all  legitimate  enterprise." 

Every  mining  man  can  undoubtedly  recall  numerous 


INTRODUCTORY.  H 

cases  where  labor  has  been  expended  on  worthless 
minerals  which  a  very  slight  knowledge  of  mineralogy 
would  have  saved.  The  writer  has  seen  a  shaft  sunk 
on  a  body  of  black  obsidian  (volcanic  glass),  under 
the  belief  that  it  was  anthracite  coal.  In  another  case 
the  men  were  prospecting  for  coal  in  a  narrow  canon 
between  basaltic  walls,  on  the  strength  of  a  few  pieces 
of  carbonized  wood  in  the  gravel  beds  filling  the 
gorge.  In  another  instance  several  shafts  were  sunk 
on  a  deposit  of  red  jaspery  clay,  carrying  specks  of 
iron  pyrite,  the  prospector  mistaking  it  for  cinnabar 
on  account  of  its  bright  red  color,  having  probably 
heard  that  cinnabar  was  red,  without  knowing  that 
usually  it  assumed  that  brilliant  tint  only  when 
scratched  or  pulverized.  For  years  a  prospector  in 
Washington  spent  money  on  and  clung  to  the  idea 
that  he  could  develop  an  iron  mine  out  of  a  body  of 
clay  slate,  mixed  with  quartz  and  large  quantities  of 
iron  pyrite,  not  knowing  that  the  sulphur  of  the 
pyrite  was  a  most  undesirable  constituent  in  iron, 
and  that  there  was  no  probability  of  the  deposit 
changing  its  character.  Then  again  tin  is  an  ever- 
recurring  ignis  fatuus.  Recently  the  writer  was 
assured  in  perfect  good  faith  by  a  person  willing  to 
prove  his  faith  by  his  works  (if  he  could  get  some  one 
to  join  him),  that  he  had  pounded  pure  tin  out  of  the 
ore  in  a  common  mortar;  and  another  could  not  be 
convinced  that  the  polishing  of  the  mortar  while 
grinding  so-called  tin  ore  was  not  a  coating  of  that 
metal,  the  iron  as  he  called  it  being  "galvanized!" 
Such  stories  lie  at  the  bottom  of  many  a  newspaper 
item,  and  hundreds  of  such  wild-goose  propositions 
come  before  the  mining  engineer  and  mining  men 
generally  every  year.  But  many  a  prospector  will 
spend  the  best  years  of  his  life  on  such  schemes,  and 
not  infrequently  drag  his  equally  uninformed  friends 
into  them,  for  want  of  a  little  knowledge  so  easily 
obtained. 


12  PROSPECTING  AND  VALUING  MINES. 

Yet  another  common  source  of  loss  is  the  failure  to 
ascertain  the  true  value  of  the  ore  and  the  probable 
character  and  quantity  before  erecting  expensive 
hoisting  and  reduction  works.  Both  of  these  subjects 
are  more  fully  treated  of  in  Chapter  II.,  and  mention 
of  them  is  here  made  only  to  emphasize  the  impor- 
tance of  extreme  care  in  all  these  points.  Just  as  an 
ounce  of  quicksilver  if  thoroughly  mixed  with  a  ton 
of  sand  will  show  its  presence  in  every  pound  of  the 
latter  on  washing,  so  a  very  small  amount  of  free  gold 
will  make  a  big  showing  in  a  ton  of  broken  white 
quartz.  The  writer  has  seen  a  dump  on  which  free 
gold  could  be  easily  found  but  which  gave  a  return  of 
less  than  $5  per  ton  when  milled.  Coarse  gold  ores, 
though  the  prettiest  of  specimens,  are  exceedingly 
deceptive,  and  extreme  caution  is  absolutely  essential 
to  safety.  Gold  is  so  easily  extracted  from  the  ore 
when  native  (free)  that  to  ask  for  capital  to  develop 
prospects  reported  to  assay  $50,  $100  and  upward  per 
ton  is  sure  to  excite  suspicion  in  the  minds  of  those 
acquainted  with  the  subject,  as  with  a  donkey,  a  little 
water,  a  few  pounds  of  quicksilver,  and  a  fair  share  of 
patience  and  physical  strength  the  owner  of  such  a 
prospect  can  create  his  own  capital,  provided  always 
that  the  assay  represents  the  whole  mass  and  not  some 
individual  specimen. 

Costly  mistakes  are  also  made  through  want  of 
knowledge  of  the  way  in  which  ore  is  distributed 
through  the  vein.  Experience  has  taught  the  writer 
that  not  a  small  proportion  of  those  who  might  be  sup- 
posed to  be  somewhat  familiar  with  the  subject 
imagine  that  a  vein  has  a  uniform  thickness  like  a 
plank,  and  like  the  latter  is  made  up  of  the  same 
material  throughout,  so  that  there  ought  to  be  only 
two  kinds  of  veins,  those  which  never  carry  ore  and 
those  whicl}  are  continually  in  ore.  Excessive  antici- 
pations and  undue  depression  result  from  such  views, 
a  diminution  in  thickness  being  never  looked  for  on 


INTRODUCTORY.  13 

the  one  band  or  an  increased  quantity  on  the  other. 
Probably  no  vein  carries  ore  from  wall  to  .wall  through- 
out its  entire  length.  The  probabilties  are  altogether 
against  such  a  condition.  The  spotted  character  of 
most  ore  bodies  is  well  shown  in  pi.  8,  which  is  a 
copy  of  a  longitudinal  section  of  the  Dolcoath  mine 
(sometimes  called  Wheal  Dolcoath)  in  Cornwall,  Eng- 
land. The  length  on  the  vein  covered  by  the  section 
is  about  3,300  ft.  and  the  depth  about  2,300  ft.  The 
longitudinal  elevation  of  the  Comstock  lode  prepared 
by  the  writer  for  the  U.  S.  Geological  Survey  shows 
vastly  greater  blank  spaces.  A  want  of  knowl- 
edge of  how  ore  occurs  in  veins  has  ruined  many  a 
mine.  Intimately  connected  with  this  subject,  which 
is  treated  at  length  when  speaking  of  the  structure  of 
veins,  is  the  change  in  the  character  of  ore  in  depth 
from  various  causes,  frequently  resulting  in  the  aban- 
donment of  the  mine  on  reaching  the  water  level. 
Free  gold  ores  may  change  into  iron  pyrites  of  a  much 
lower  grade,  yet  more  costly  to  work,  and  rich  copper 
ores  may  give  out  entirely,  being  replaced  by  low- 
grade  iron  pyrite  carrying  a  small  percentage  of  copper 
too  lean  to  pay  the  cost  of  working. 

Failure  may  also  occur  from  want  of  care  in  protect- 
ing the  interior  workings,  resulting  in  extensive  caves 
which  may  involve  the  loss  of  a  shaft  or  an  entire  ore 
body  by  mixing  it  with  waste  from  the  walls  and 
reducing  its  value  below  the  limit  of  profitable  extrac- 
tion. Even  outside  of  coal  mining  such  accidents  are 
far  from  infrequent.  Only  those  who  have  seen  the 
evidence  of  the  immense  power  developed  by  the  pres- 
sure of  large  masses  of  earth,  or  even  by  its  expansion 
under  some  circumstances,  can  realize  its  amount  or 
extent.  Both  in  coal  and  gold  gravel  mining  the  floor 
of  a  drift  is  apt  to  rise  up  or  "creep,"  from  the  pres- 
sure of  the  surrounding  mass  squeezing  Jbhe  bottom 
upward  into  the  space  made  vacant  by  the  drift  or 
tunnel.  This  occurs  especially  when  the  floor  is  soft 


14  PROSPECTING  AND  VALUING  MINES. 

(or  as  the  gravel  miners  say,  "cheesy").  In  one  in- 
stance in  California  the  writer  has  seen  a  tunnel 
driven  through  the  rim,  or  bed  rock  of  a  gravel  chan- 
nel, as  might  be  the  lower  tunnel  in  pi.  11,  fig.  2,  which, 
when  it  broke  through  into  the  channel,  encountered 
a  body  of  clay  and  gravel,  so  soft  that  it  was  squeezed 
by  the  weight  above  into  the  tunnel  like  a  huge  sau- 
sage, nearly  as  fast  as  it  could  be  removed.  In  another 
case  of  a  tunnel  being  driven  to  reach  some  old  work- 
ings,the  miners  were  furnished'with  a  grade-gauge  by 
which  to  lay  the  track,  so  that  with  one  end  laid  upon 
the  older  portion,  the  new  sills  could  be  put  in  as  the 
tunnel  progressed,  on  the  correct  slope  to  connect 
with  the  old  workings.  Owing  to  the  creeping  of  the 
bottom  during  the  progress  of  the  work,  each  set  of 
track  timbers  as  it  was  laid  was  squeezed  upward 
before  the  time  came  to  lay  the  following  section,  and 
the  tunnel  came  out  much  too  high,  and  was  a  failure 
in  consequence  of  thus  having  acquired  too  steep  a 
grade. 

Finally,  litigation  resulting  from  defective  locations 
is  a  fruitful  source  of  trouble,  involving  a  heavy  tax. 
on  the  resources  of  the  mine.  Through  a  forgetful- 
ness  of  the  importance  of  determining  the  direction  of 
lode  before  making  the  location  it  sometimes  happens 
that  the  lode  passes  out  of  the  side  lines  into  the  prop- 
erty of  adjacent  owners,  instead  of  extending  the  full 
length  of  the  claim,  and  the  mine  not  only  loses  a  con- 
siderable length  of  the  lode,  but  becomes  involved  in 
vexatious  questions  of  boundary  lines,  the  litigation 
over  which  may  absorb  all  the  revenues  or  even  leave 
the  mine  in  debt. 

Such  are  some  of  the  causes  which  lead  to  failure  of 
mining  enterprises.  They  will  be  seen  to  be  generally 
due  to  want  of  knowledge  on  the  part  of  the  prospec- 
tor, investor  and  managers  of  the  enterprises  of  some 
special  point  in  their  respective  capacities.  It  must 
not,  however,  be  understood  that  all  failures  result 


INTRODUCTORY.  15 

from  this  cause.  There  are  cases  where  circumstances 
arise  which  could  not  possibly  be  foreseen  and  guarded 
against,  and  the  judgment  of  the  very  best  men  may 
err,  for  we  are  none  of  us  infallible;  but  it  is  desired 
to  show  that  at  least  very  great  losses  might  be  avoided 
if  there  were  a  more  general  understanding  and  appre- 
ciation of  the  fact  that  to  be  a  successful  mining  man 
requires  a  combination  of  mental  and  physical  quali- 
ties such  as  few  other  callings  demand;  and  that  min- 
ing is  a  business  calling  for  special  training  just  as 
certainly  as  technical  knowledge  is  essential  to  the 
watchmaker  or  shipbuilder. 

The  present  chapter  has  been  practically  a  presenta- 
tion of  failure  after  failure,  and  these  would  be  often 
laughable  if  the  incidents  were  not  so  pathetic.  The 
good  faith  of  the  men  who  made  the  mistakes  quoted 
as  samples  was  unquestionable,  and  only  intensifies 
the  pity  felt  for  their  misdirected  energies.  Fortu- 
nately there  is  a  brighter  side.  The  presentation  has 
only  been  made  out  of  abundant  precaution.  There  is 
no  more  fascinating  occupation  in  the  world  than  min- 
ing; none  that  keeps  all  the  faculties  so  fully  alive, 
and  no  sensation  so  pleasant  as  the  handling  of  the 
bullion  after  a  successful  run  ! — while  it  is  not  unlikely 
that  the  percentages  of  successes  would  prove  as  great 
as  in  most  of  the  other  great  industries. 


CHAPTER  II. 
WHAT  CONSTITUTES  A  MINE. 

A  MERE  bunch  of  ore  will  not  make  a  mine;  and  it 
may  be  well  to  examine  the  factors  which  really  go  to 
constitute  a  mine.  A  "mine/5  then,  is  any  deposit  of 
mineral  which  can  be  worked  at  a  profit;  that  is  to 
say,  before  the  deposit  is  exhausted  it  must  have  re- 
turned to  the  "adventurers"  (as  the  owners  or  operators 
are  frequently  called  in  England)  the  original  pur- 
chase money,  the  entire  cost  of  the  improvements  of 
every  nature,  and  the  entire  cost  of  working  the  ore, 
whether  it  be  mining,  milling,  smelting,  transporta- 
tion, supplies,  superintendence,  or  office  expenses, 
together  with  a  fair  interest  on  the  money  invested. 
If  we  charge  against  the  salable  product  all  the  ex- 
penses except  purchase  money  and  plant,  we  arrive 
at  the  running  cost  of  production  per  ton,  and  if  the 
selling  price  per  ton  be  greater  than  this,  the  differ- 
ence per  ton  will  go  to  the  account  of  purchase  money, 
development  and  plant;  and  there  must  be  in  the 
deposit  at  least  a  sufficient  number  of  tons  of  ore, 
which,  multiplied  by  the  profit  per  ton,  will  extin- 
guish the  original  cost  of  mine  and  improvements,  it 
being  supposed  that  repairs  to  reduction  or  hoisting 
works,  etc.,  are  charged  to  the  cost  of  producing  and 
milling  or  smelting  the  ore. 

For  instance,  if  the  purchase  money  and  original 
plant  cost  $200,000,  and  the  profit  per  ton  over  ex- 
penses of  production  and  reduction  is  $10  per  ton,  the 
mine  must  produce  20,000  tons,. at  least,  before  it  can 


WHAT  CONSTITUTES  A  MINE.  17 

be  called  self-sustaining,  and  a  surplus  over  that 
amount  to  cover  reasonable  interest.  If  the  ore  be 
free  gold  quartz,  or  free-milling  silver,  about  13  cu. 
ft.  in  place  will  weigh  1  ton  of  2,000  lb.,  so  that  the 
cubic  contents  of  the  20,000  tons  would  be  260,000 
cu.  ft.,  equal  to  a  block  of  ground — 

260  ft.  deep  by  1000  ft.  long,  if  the  vein  be  1  ft.  thick. 
130  ft,  deep  by  1000  ft.  long  if  the  vein  be  2  ft.  thick. 
65  ft.  deep  by  1000  f  r.  long,  if  the  vein  be  4  ft.  thick. 

or,  if  the  ore  deposit  be  only  500  ft.  in  length — 

520  ft.  deep  by  500  ft.  long,  if  the  vein  be  1  ft.  thick. 
260  ft.  deep  by  500  ft.  long,  if  the  vein  be  2  ft.  thick. 
130  ft.  deep  by  500  ft.  long,  if  the  vein  be  4  ft.  thick. 

but  if  the  ore  shoot  be  only  100  ft.  in  length — 

2,600  ft.  deep  by  100  ft.  long,  if  the  vein  be  1  ft.  thick. 

1,300  ft.  deep  by  100  ft.  long,  if  the  vein  be  2  ft.  thick. 

650  ft.  deep  by  100  ft.  long,  if  the  vein  be  4  ft.  thick. 

From  the  foregoing  it  is  evident  that  the  length  of 
the  ore  body  is  of  immense  importance,  as  the  cost  of 
working  a  mine  increases  with  depth  at  a  constantly 
increasing  rate;  and  the  longer  the  ore  shoot,  the 
shallower  will  be  the  workings  to  accomplish  the  same 
results.  If  the  shoot  be  only  100  ft.  long  it  will  be 
necessary  to  sink  ten  times  as  deep,  at  a  heavy  ex- 
pense, as  if  it  were  1,000  ft.  Of  course  this  is  assum- 
ing a  theoretical  regularity  of  deposit. 

In  order  that  similar  calculations  may  be  made  on 
other  classes  of  ore,  the  following  table  gives  the 
specific  gravity  of  the  principal  metals  and  their  prin- 
cipal ores;  the  weight  of  1  cu.  ft.  of  each,  and  the 
number  of  cubic  feet  which  will  equal  a  ton  of  2,000 
lb.  As  the  specific  gravities  of  the  ores  are  taken 
from  pure  specimens,  generally  crystallized,  they  will 
give,  as  a  rule,  quantities  too  small  in  the  column  of 
cubic  feet  per  ton,  as  the  ores  in  run-of-mine  are 
seldom  free  from  impurities;  so  that  a  somewhat 


18 


PROSPECTING  AND   VALUING  MINES. 


greater  number  of  feet  should  be  assumed  in  making 
the  calculation,  to  be  on  the  safe  side: 


SPECIFIC  GRAVITIES  OF  METALS  AND  MINERALS. 


Metals  and  Minerals. 

Specific  Gravity. 

Weight  of 
cubic  ft. 
Pounds. 

Number  of 
cubic  feet 
to  ton. 

Range. 

Average. 

Gold  
Silver           .        

15.60-19.33 
10.10-11.10 
5.22-7.36 

19.30 
10.50 
6.08 
8.84 
4.20 
5.00 
4.80 
2.20 
13.58 
9.00 
11.44 
7.50 
6.00 
7.00 
4.10 
4.20 
3.46 
7.21 
7.69 
5.00 
4.90 
3.80 
5.00 
6.20 
4.41 
7.35 
6.75 
6.70 
4.57 
2.65 
3.18 
4.51 
1.00 

1206.25 
656.25 
380.00 
552.50 
262.50 
312.50 
300.00 
137.50 
846.  (X) 
562.50 
715.00 
468.75 
375.00 
437.50 
256.25 
252.00 
216.25 
450.00 
480.00 
312.50 
306.25 
237.50 
312.50 
387.50 
275.62 
459.00 
421.87 
418.00 
285.62 
165.62 
198.75 
281.87 
62.50 

1.66 
3.05 
5.26 
3.62 
7.62 
6.40 
6.66 
14.62 
2.36 
3.55 
2.80 
4.27 
5.33 
4.57 
7.84 
7.95 
9.25 
4.44 
4.17 
6.40 
6.53 
8.42 
6.40 
5.16 
7.25 
4.35 
4.74 
4.78 
7.00 
12.08 
10.06 
7.01 
32.90 

Silver  free  ores 

Copper                

Copper  pyrite 

4.10-4.30 
4.40-5.50 
4.50-5.10 
2.00-2.40 

Copper  purple  

Copper   gray  

Copper  silicate    

CinnrJbar  

9.00 

Lead      

Lead  galena 

7.257.70 
5.40-6.47 

Lead  carbonate  

Zinc 

Zincblende         

3.90-4.20 
4.00-4.45 
3.43-3.49 

2jinc    carbonate 

Zinc  silicate    .... 

Iron,  cast  

Iron  wrought    .  . 

Iron    magnetite  

Iron  hema  ti  te 

Iron  limonite  

Iron  pyrite 

4.83-5.20 
6.00-6.40 
4.32-4.49 

Iron,  arsenical  pyrite.. 
Iron  chrome 

Tin   

Tin  oxide 

6.40-7.10 

Antimony  

Antimony  sulphide  
Quartz  

4.52-4.62 

Fluorspar 

3  .01-3.25 
4.30-4.72 

Sulphate  of  baryta.  .... 
Water  

But  as  we  may  frequently  want  the  weight  and  bulk 
of  ores  made  up  of  several  minerals,  the  following  ex- 
amples will  show  how  the  weight  per  cubic  foot  of  such 
ores  may  be  obtained  : 

Calculation  by  Bulk. — Take  an  ore  containing  say 
50%  of  its  bulk  in  galena,  25%  in  arsenical  pyrite, 
8%  in  zincblende,  and  17%  in  quartz.  By  reference 
to  the  foregoing  table  we  have : 


WHA  T  CONSTITUTES  A  MINE.  19 

0.50  of  1  cu.  ft.  of  galena  =  234.37  Ib. 

0.25  of  1  cu.  ft.  of  arsenical  pyrite  =    96.88  Ib. 

0.08  of  1  cu.  ft.  of  zinc  blende  =    20.50  Ib. 

0.17  of  1  cu.  ft.  of  quartz  =    28.15  Ib. 

1.00  379.801b. 

Calculation  by  Weight. — But  if  it  be  desired  to 
ascertain  the  weight  of  1  cu.  ft.  of  ore  containing  the 
same  minerals  estimated  by  weight  instead  of  bulk,  we 
can  calculate  the  bulk  of  a  known  definite  weight,  say 
1,000  Ib.,  and  instantly  determine  the  weight  of  1 
cu.  ft.  by  simple  proportion.  Out  of  the  1,000  Ib.  we 
shall  have : 

500  Ib.  galena  -f-  468.75  =  1.068  cu.  ft. 

250  Ib.  arsenical  pyrite  —  387.50  =  0.645  cu.  ft. 
80  Ib.  zincblende  4-  256.25  =  0.312  cu.  ft. 

170  Ib.  quartz  —  165.62  -  1.026  cu.  ft. 


1000  3.051  cu.  ft.     - 

or  6.102  ou.  ft.  per  ton.     By  proportion  the 

Galena  =  0.350  of  1  cu.  ft.  X  468.75  =  164.06  Ib. 

Arsenical  pyrite  =  0.212  of  1  cu.  ft.  X  387.50  =    82.15  Ib. 

Zincblende  =  0.103  of  1  cu.  ft.  X  256.25  =    26.14  Ib. 

Quartz  =  0.336  of  1  cu.  ft.  X  165.62  =    55.65  Ib. 

1.000  328.00 

All  other  combinations  may  be  worked  out  by  these 
examples.  Assuming  the  profit  on  this  class  of  ore  to 
be  the  same  as  that  of  tile  free  gold  ore  given  pre- 
viously ($10  per  ton),  it  is  clear  that  the  ore  body 
would  only  have  to  be  about  half  the  dimensions  before 
quoted  to  secure  the  same  results,  as  1  ton  only  oc- 
cupies about  half  the  space  of  the  first  illustration. 

Favorable  Conditions. — If  the  mine  is  so  located 
that  its  product  can  be  sold  to  independent  reduction 
works,  it  is  plain  that  smaller  ore  bodies  may  be  profit- 
ably extracted;  and  yet  smaller  ones  if  the  mine  be 
worked  by  the  original  discoverers,  and  the  ore  is  of  a 
grade  high  enough  to  yield  a  margin  of  profit  over  the 
cost  of  extraction  and  transportation  to  market,  as  in 
the  first  case  there  are  no  reduction  works  to  be  paid 
for  out  of  the  profits  of  the  mine,  and  in  the  latter 


20  PROSPECTING  AND  VALUING  MINES. 

case,  neither  reduction  works  nor  purchase  money. 
Any  ore  body  fulfilling  these  conditions  may  properly 
be  called  a  mine,  and  it  is  such  that  the  prospector  is 
looking  for. 

Mining  Compared  with  other  Business. — Only  an 
exceedingly  small  proportion  of  the  locations  made 
ever  develop  into  mines,  probably  not  more  than  one 
in  a  hundred.  On  the  Comstock  lode,  out  of  several 
thousand  locations  on  record,  less  than  fifty  had  any 
large  amount  of  development,  and  still  fewer  ever  paid 
dividends;  yet  the  gross  product  of  bullion  from  the 
comparatively  few  active  mines  was  enormous.  Simi- 
lar conditions  hold  good  in  most  other  mining  camps; 
but  it  is  likely  that  the  percentage  of  success  in  min- 
ing enterprises  is  fully  as  great  as  in  almost  any  other 
line  of  business — certainly  as  great  if  the  same  amount 
of  care  has  been  exercised  in  selecting  the  property  as 
is  usual  in  opening  a  new  store  or  hotel.  But  the 
miner  must  always  remember  that  while  the  business 
of  the  store  may  expand  indefinitely,  he  is  from  the 
very  start  living  on  his  capital  (the  total  amount  of  ore 
in  the  mine),  and  that  this  diminishes  daily  the  more 
rapidly  as  the  output  is  enlarged;  while  after  reach- 
ing its  extreme  productiveness  the  later  stages  of  a 
mine  are  merely  like  realizing  on  the  assets  of  a  fail- 
ing business. 

VALUATION  OF  MINING  PROPERTY. — The  value  of  min- 
ing property  is  therefore  not  to  be  estimated  by  the 
amount  of  the  dividends  it  may  be  paying  at  any  par- 
ticular time,  but  by  the  number  and  value  of  the  divi- 
dends it  will  be  able  to  pay  in  the  future. 

Relation  of  Profits  to  Price. — Thus,  because  a  mine 
has  just  paid  an  annual  dividend  of  $1,000,000, 
it  does  not  follow  that  the  mine  is  to  be  valued  at 
$10,000,000  (which  would  make  the  dividend  equal  to 
10%),  because  it  can  only  be  worth  that  figure  to  pur- 
chasers for  investment  if  it  is  able  to  disburse  that 
amount  or  over  in  dividends  in  the  future  with  a  fair 


WHAT  CONSTITUTES  A  MINE.  21 

interest  on  the  investment  in  addition.  If  the  divi- 
dends were  distributed  over  ten  years  at  the  rate  of 
$1,000,000  per  annum,  the  investors  would  just  receive 
the  original  amount  paid  without  interest,  so  th&t  if 
the  investors  are  to  receive  interest  at  the  rate  of  10% 
on  the  money  invested,  the  mine  must  pay  another 
$5,500,000  in  dividends,  making  $15,500,000  in  all, 
to  be  worth  $10,000,000  as  an  investment. 

But  it  might  be  that  the  mine  had  reached  its  maxi- 
mum productiveness  when  it  paid  the  million-dollar 
dividend,  and  the  ore  bodies  in  sight  began  to  show 
signs  of  exhaustion.  In  such  a  case  the  extreme  value 
to  an  investor  would  only  be  the  actual  profit  on  the 
exposed  reserves,  which  might  be  small. 

The  chance  of  finding  new  ore  bodies  cannot  be 
expressed  in  figures.  One  of  the  great  sources  of  dis- 
appointment in  mining  enterprises  is  the  over-estima- 
tion of  mining  values,  mistaking  capital  for  profit. 
Another  is  the  payment  of  unjustifiable  prices,  not 
only  for  properties  with  considerable  development, 
but  for  holes  in  the  ground  or  mere  naked  locations. 
It  is  true  that  very  often  the  purchaser  expects  to  sell 
again  at  a  profit  and  not  to  work  the  property,  but 
then  he  has  removed  his  dealings  from  mining  to  the 
realms  of  speculation,  and  has  no  reason  to  grumble  if 
failure  follows  the  change. 

Ore  "in  Sight." — Practically  the  value  of  a  mining 
location  is  the  net  profit  on  the  ore  exposed.  If  there 
is  any  promise  in  the  surroundings  of  a  future  to  the 
location,  this  definition  might  possibly  be  enlarged  to 
the  gross  value,  the  purchaser  looking  to  developments 
made  with  his  own  capital  for  reimbursement  of  the 
original  investment  and  profit.  The  value  then  of  the 
majority  of  original  locations  is  very  small.  Many  of 
them  are  absolutely  valueless,  being  made  upon  a  mere 
stain  or  a  slight  difference  in  the  color  of  a  certain 
streak  or  layer  of  rock,  or  the  presence  of  a  little  iron 
pyrite  in  a  particular  seam,  which  only  means  that 


22  PROSPECTING  AND  VALUING  MINES. 

there  has  been  decomposition  of  some  of  the  horn- 
blende or  allied  mineral  contained  therein.  If,  how- 
ever, there  is  actually  valuable  ore  in  sight,  this  must 
be  carefully  measured  for  length  and  breadth,  and  if 
these  measurements  show  a  continuous  workable  body 
the  price  of  the  location  might  possibly  be  the  value 
of  this  ore  to  a  depth  of  a  few  feet,  according  to  the 
width  of  the  ore  exposed. 

The  situation  is  improved  by  the  sinking  of  a  shaft 
or  the  running  of  a  tunnel,  but  a  single  shaft  does  not 
prove  the  existence  of  much  ore.  It  simply  shows  its 
presence  at  that  particular  point  to  a  certain  depth 
and  the  quantity  in  sight  will  be  the  two  triangles  a 
and  b  in  pi.  13,  fig.  1,  multiplied  by  the  average  thick- 
ness. If  two  shafts  have  been  sunk,  as  in  pi.  13, 
fig.  2,  we  can  call  the  shaded  portion  "in  sight. "  If 
the  development  be  a  shaft  with  drift  from  the  bottom, 
as  in  pi.  13,  fig.  3,  we  can  still  only  consider  in  sight 
the  portion  shaded,  with  a  probability  of  more  because 
of  the  ore  in  the  bottom  of  the  drift  c.  The  same  will 
be  the  case  if  a  tunnel  is  run  on  the  vein  as  B  in  pi. 
13,  fig.  4,  but  if  the  bottom  of  the  shaft  A  is  in  ore 
and  the  face  of  the  tunnel  B  also,  part  of  the  block  D 
may  be  added  to  the  probable  reserves  (unless  the  ore 
is  growing  smaller  in  width),  though  it  cannot  be  con- 
sidered actually  in  sight,  by  which  we  understand  a 
block  of  ground  exposed  on  all  sides,  as  in  pi.  13,  fig. 
5,  where  the  blocks  E  E  are  actually  in  sight  and 
DDD  can  be  added  as  probabilities,  along  with  an 
unknown  quantity  below  the  lower  drift  at  F.  In  all 
the  foregoing  examples  it  is  supposed  that  the  outcrop 
is  the  extreme  workable  length  of  the  ore,  and  that 
none  of  the  underground  workings  have  been  run  out 
of  ore,  so  that  we  have  no  means  of  judging  whether 
the  ore  body  is  holding  its  own  in  size,  or  increasing 
or  diminishing;  but  if  the  explorations  have  developed 
the  facts  shown  in  pi.  13,  fig.  6,  we  can  afford  to  be 
liberal  in  the  estimate  of  the  probable  reserves,  as  dis- 


WHAT  CONSTITUTES  A  MINE.  23 

fcinguished  from  ore  in  sight  (shaded),  because  it  is 
evident  that  the  ore  body  is  not  at  present  diminish- 
ing in  horizontal  length,  and  may  therefore  be  exten- 
sive in  depth.  If,  on  the  contrary,  the  result  has  been 
as  shown  in  pi.  13,  tig.  7,  we  must  be  exceedingly  con- 
servative, as  the  ore  body  is  evidently  pinching  out 
downward  as  well  as  laterally. 

It  would  be  easy  to  extend  these  illustrations,  but 
enough  has  been  said  to  show  the  basis  on  which  esti- 
mates of  quantity  of  ore  in  sight  in  a  mine  are  arrived 
at,  and  also  to  show  that  work  is  the  only  thing  which 
can  give  value  to  a  location.  Because  a  prospector  has 
been  able  to  make  two  or  three  locations  or  more,  in  a 
season's  work,  it  does  not  follow  that  they  are  actually 
worth  the  time  spent  in  securing  them.  The  value  of 
an  article  is  not  the  price  paid  for  it,  or  its  actual  cost 
to  the  owner.  The  price  paid  may  have  been  out  of 
all  proportion  to  the  value,  or  the  actual  cost  of  the 
article  may  have  been  so  reduced  by  improved  ma- 
chinery that  it  can  be  bought  for  a  mere  fraction  of 
the  Hum  paid  for  the  original  production.  So  the 
value  of  a  mining  property  is  not  to  be  estimated  by 
what  it  has  cost  the  parties  offering  it  for  sale,  but  by 
the  profit  it  will  realize  to  the  purchaser. 

Grade  of  Ore. — But  even  a  large  body  of  ore  may  be 
valueless  if  the  cost  of  extraction  and  reduction  equal 
or  exceed  the  value  of  the  metal  extracted  from  the 
ore;  nor  does  it  follow  that,  because  ore  of  a  certain 
grade  has  been  profitably  worked  in  one  mining  camp, 
this  will  hold  good  for  all  others,  as  the  conditions 
vary  so  widely.  If  everything  in  the  shape  of  sur- 
roundings is  favorable,  a  very  low-grade  ore  may  prob- 
ably yield  a  profit,  while  in  another  camp  a  much 
richer  ore  may  bring  the  miners  into  debt. 

Sampling. — Where  no  work  has  been  done  on  a  loca- 
tion which  shows  enough  of  an  outcrop  to  justify  a 
more  extended  examination,  we  can  simply  sample  the 
croppings  thoroughly  to  ascertain  which  portions  of 


24  PROSPECTING  AND  VALUING  MINES. 

them  carry  mineral  enough  to  be  valuable,  and  the 
character  of  this  mineral,  because  it  is  seldom  that  the 
outcrop  is  of  uniform  value  throughout  its  length. 
This  is  not  done  by  taking  small  hand  samples  here 
and  there,  for  the  most  honest  man  is  not  honest 
enough  to  be  able  to  select  a  fair  average  in  such  a 
way.  A  clean  cut  across  the  entire  width  of  the  pay 
streak  should  be  taken  at  stated  intervals,  to  avoid  the 
interference  of  the  judgment,  or  the  deception  of  the 
eye,  and  each  of  these  samples  should  be  thoroughly 
broken  on  a  clean  floor,  mixed,  spread  out  in  a  thin 
sheet  and  quartered.  One  of  these  quarters  should  be 
broken  still  finer,  remixed  and  again  quartered.  This 
will  probably  bring  the  sample  down  to  such  a  size 
that  its  entire  mass  can  be  ground  to  coarse  "pulp. " 

Assaying. — From  this  pulp  samples  should  be  fur- 
nished to  two  independent  assayers,  retaining  the 
balance  for  further  tests  should  there  be  much  differ- 
ence between  the  results  obtained  from  the  assayers 
(between  whom  there  can  be  no  collusion,  as  the  look 
of  the  pulp  will  not  betray  any  peculiar  external  char- 
acters of  the  ore  by  which  its  identity  might  have  been 
suspected).  To  furnish  both  assayers  with  the  same 
pulp  is  also  fairer  to  the  assayers,  because  they  are  both 
placed  on  the  same  footing,  which  is  not  the  case  when 
a  piece  of  ore  is  broken  into  two  pieces  and  one-half 
given  to  each  (except  in  a  few  exceptional  cases),  as 
there  may  be  sufficient  difference  in  the  composition 
of  the  two  pieces,  especially  in  a  complex  ore,  to  war- 
rant considerable  discrepancies  in  the  results  obtained, 
which  would  naturally  throw  a  shadow  of  doubt  upon 
the  entire  investigation.  In  gold  ores  this  is  very 
liable  to  be  the  case.  A  small  sprinkling  of  telluride 
of  gold  (looking  like  lead)  might  run  one  specimen  up 
into  the  thousands  per  ton  and  the  other  give  only 
tens.  Care  should  be  taken  to  distinguish  between 
mere  specimens  and  true  average  samples. 

In  this  way  only  can   reliable  results  be  obtained^ 


WHA  T  CONSTITUTES  A  MINE.  £5 

but  if  the  ore  prove  to  carry  much  gold,  even  then 
they  will  not  be  entirely  satisfactory,  nor  will  they 
indicate  the  true  commercial  value  of  the  ore  unless 
determination  of  the  nature  and  quantity  of  undesir- 
able mineral  constituents  be  made,  if  such  are  sus- 
pected from  examination  of  the  ore  as  taken  from  the 
vein. 

When  gold  is  found  only  in  combination  with  other 
minerals  it  is  usually  disseminated  through  them  in 
such  fine  particles  that  the  distribution  is  compara- 
tively uniform  and  an  assay  will  be  satisfactory,  in  so 
far  as  the  amount  of  gold  in  the  ore  is  concerned;  but 
when  a  portion  of  the  gold  has  become  free,  or  liber- 
ated from  the  associated  minerals  (as  the  various  forms 
of  pyrites)  by  the  decomposition  of  the  latter,  or  still 
more  so  when  a  portion  of  it  has  never  been  in  com- 
bination, but  is  scattered  through  the  mass  in  particles 
of  varying  dimensions,  the  assays  will  be  in  all  prob- 
ability valueless,  because  they  may  accidentally 
include  quite  a  large  piece  of  gold  (comparatively 
speaking),  and  this  multiplied  by  the  thousands  of 
times  which  an  assay  sample  is  contained  in  a  ton 
would  give  very  high  results,  while  the  next  sample, 
not  containing  such  a  piece,  may  only  show  very  small 
or  insignificant  returns.  This  may  easily  occur,  as 
the  gold  cannot  readily  be  ground  fine  enough  to  pass 
through  the  sieve  with  the  other  pulp,  but  must  be 
mixed  with  the  pulp  after  it  is  ground,  and  thus  the 
chance  of  getting  a  fair  average  sample  is  exceedingly 
small. 

Horn  Spoon. — Every  prospector  should  carry  a  horn 
spoon,  made  by  cutting  off  the  belly  of  a  large  cow's 
horn  and  polishing  the  inside  with  sandpaper,  as  in 
pi.  13,  fig.  8;  or  he  can  obtain  an  iron  one  of  the  same 
shape,  but  having  one-half  galvanized  to  better  show 
black  ore  minerals.  Such  a  spoon  cau  be  carried  in  the 
pocket,  and  if  the  presence  of  free  gold  in  the  ore  be 
suspected  a  few  minutes  will  suffice  to  grind  up  a 


26  PROSPECTING  AND  VALUING  MINES. 

sample  on  a  smooth  flat  rock  with  a  small  hand  stone, 
and  wash  it  out  in  the  nearest  water  hole,  which  can 
be  very  much  smaller  than  is  required  for  the  gold 
pan,  a  bucket  or  even  a  wash  basin  being  amply  large 
enough.  The  very  finest  colors  may  be  detected  by 
this  method.  If  any  are  found,  a  sample  large  enough 
to  secure  a  fair  average  should  be  taken,  and  the 
entire  mass  reduced  to  pulp.  All  screenings  which  will 
not  pass  through  the  sieve  should  be  saved  until  the 
process  is  complete,  and  then  returned  to  the  pulp,  the 
weight  of  which  while  dry  should  be  carefulbr  ascer- 
tained. The  pulp  should  then  be  mixed  with  water, 
adding  sufficient  quicksilver  to  amalgamate  the  free 
gold,  and  thoroughly  worked  over  to  insure  complete 
contact  of  all  the  gold  with  the  mercury.  The  amal- 
gam thus  obtained  may  be  reduced  to  a  button  with 
the  blowpipe,  care  being  taken  not  to  inhale  the  mer- 
cury fumes,  and  then  by  simple  proportion  the  amount 
of  free  gold  per  ton  may  be  ascertained  with  reason- 
able accuracy,  if  the  average  of  several  tests  be  taken. 
Thus,  if  5  Ib.  of  ore  contain  25c.,  2,000  Ib.  will  contain 
$100. 

Segregating  Ore  Minerals. — An  assay  of  the  pulp 
which  is  left  will  give  the  amount  of  gold  in  combina- 
tion with  the  "sulphurets"  per  ton,  and  the  sum  of 
the  two  the  total  value  of  the  ore.  Also,  by  washing 
out  the  sand  the  percentage  of  sulphides  per  ton  of 
ore  may  be  ascertained,  and  an  assay  of  these  concen- 
trated sulphides  will  give  the  value  of  the  concentrates 
per  ton,  and  enable  us  to  formulate  a  plan  for  their 
reduction.  But  if  the  ore  contains  a  number  of  min- 
erals, such  as  iron  pyrite,  arsenical  pyrite,  zincblende 
and  galena,  we  cannot  decide  on  the  best  method  until 
we  have  ascertained,  by  assay  of  pure  samples  of  each 
of  these  minerals  separately,  which  it  is  that  contains 
the  gold,  or  whether  it  occurs  in  all  of  them  indis- 
criminately. 

In  the  case  of  smelting  ores,  such  as  galena  com- 


WHAT  CONSTITUTES  A  MINE.  27 

bioed  with  zincblende,  for  instance,  the  presence  of 
the  latter  being  detrimental  to  the  process,  it  is  espec- 
ially desirable  to  know  whether  the  blende  carries  any 
appreciable  amount  of  the  precious  metals  contained 
iu  the  ore,  as  the  difference  in  the  specific  gravity  of 
the  galena  and  blende  is  so  great  (7.5  to  4.1)  that  the 
latter  can  be  easily  separated  from  the  former  during 
the  process  of  concentration,  and  if  valueless  except 
as  zinc,  might  be  thrown  away  as  a  waste  product,  or 
reserved  for  separate  treatment  if  in  sufficient  quantity 
to  warrant  such  a  course. 

If  the  gold  is  largely  in  combination  with  iron 
pyrite  or  other  minerals  which  are  easily  decomposed 
by  exposure  to  the  action  of  air  and  water,  the  out- 
crop may  yield  a  good  showing  of  free  gold  in  rusty 
quartz,  stained  by  the  oxide  of  iron  derived  from  the 
pyrite,  which  may  suddenly  diminish  in  quantity 
when  the  permanent  water  level  of  the  mine  is  reached, 
below  which  a  large  portion  of  the  gold  may  be  in 
combination  with  the  unaltered  sulphides.  Usually 
such  gold  is  very  fine,  almost  if  not  quite  like  flour, 
but  occasionally,  as  in  iron  pyrite  from  the  slates 
near  Fiddletown,  Cal.,  the  threads  and  crystals  of  gold 
may  be  readily  seen,  and  felt  projecting  from  the 
polished  faces  of  the  large  cubes. 

Special  Cases. — In  the  case  of  ores  containing  native 
copper,  the  plan  of  taking  a  number  of  pounds  and 
working  it  in  the  same  manner  as  free  gold  is  the  only 
practicable  way  of  getting  fair  results,  and  the  same 
remark  applies  to  those  carrying  native  or  horn  silver, 
in  fact  to  all  ores  containing  minerals  which  will  not 
pulverize  and  pass  through  the  sieve;  but  ordinary 
assays  are  applicable  to  all  other  ores,  provided  care 
has  been  taken  in  preparing  the  samples  by  having 
them  large  enough  and  thoroughly  mixed,  so  as  to 
secure  average  results. 

Working  Tests,  Mill  Runs,  etc. — As  work  pro- 
gresses, the  accuracy  of  the  results  first  obtained  may 


28  PROSPECTING  AND  VALUING  MINES. 

be  tested  to  some  extent  by  actual  working  methods. 
The  facility  and  cheapness  with  which  this  may  be 
done  depend  upon  the  nearness  of  reduction  works  of 
a  suitable  character.  High-grade  ores  can  be  shipped 
over  trails  on  mule-back,  to  works  at  long  distances 
from  the  mines,  and  even  if  the  expenses  consume  all 
the  returns  the  experiment  will  be  worth  the  cost;  but 
low-grade  silver  ores  cannot  be  handled  in  this  man- 
ner. 

Arastra. — In  the  case  of  low-grade  gold  ores,  in 
which  the  gold  is  free,  which  will  not  bear  transporta- 
tion for  long  distances,  good  working  results  may  be 
obtained  from  an  arastra  built  on  the  ground,  as  it 
occupies  only  a  small  space  and  consumes  but  a  small 
amount  of  water.  The  arastra  consists  simply  of  a 
circular  floor  made  of  large  flat  rocks  carefully  laid  so 
as  not  to  leave  crevices  of  too  large  a  size  between 
them,  inclosed  by  a  low  stone  wall  of  suitable  height, 
say  2  to  3  ft.  In  the  center  is  erected  a  vertical 
spindle  supported  by  a  cross  frame,  to  which  spindle 
is  fastened  a  long  horizontal  shaft,  and  beneath  the 
latter  cross  arms  to  which  large  flat  stones  ("drags") 
are  fastened  by  means  of  short  ropes  or  chains.  When 
a  horse  or  mule  is  attached  to  the  long  shaft,  and 
driven  round  in  a  circle,  the  cross  arms  drag  the  rocks 
attached  to  them  around,  and  crush  any  ore  which 
may  be  fed  into  the  machine  between  themselves  and 
the  floor.  Of  course  the  amount  worked  daily  will 
depend  on  the  size  of  the  arastra,  and  the  softness  or 
hardness  of  the  ore,  but  it  will  do  its  work  well  and 
give  a  fair  working  test. 

Utility  of  Tests. — By  keeping  the  ore  extracted  from 
each  10,  20,  or  30  ft.  of  the  shaft  or  tunnel  by  itself, 
and  working  or  shipping  the  batches  separately,  the 
miner  will  soon  learn  which  portion  of  the  ore  body  is 
the  richest,  and  also  whether  it  is  fairly  uniform  in 
value,  or  changes  frequently  within  short  distances.  A 
few  such  tests  will  soon  determine  the  question 


WHAT  CONSTITUTES  A  MINE.  29 

whether  it  will  pay  to  build  a  road  to  the  mine,  for 
the  cost  of  such  a  road  will  ultimately  have  to  come 
out  of  the  mine. 

Roads. — Without  roads  no  heavy  machinery  can  be 
gotten  to 'the  mine  at  anything  like  reasonable  cost. 
Mining  roads  are  often  very  costly  enterprises  owing 
to  the  rough  and  broken  nature  of  the  country  which 
they  must  traverse,  and  the  want  of  them  not  infre- 
quently greatly  retards  the  development  of  otherwise 
promising  mining  districts.  As  all  the  locations  in  a 
new  district  must  share  equally  in  the  benefits  derived 
from  a  main  road  placing  them  in  ready  communica- 
tion with  the  outside  world,  the  cost  of  the  trunk  road 
should  be  raised  by  an  assessment  on  each  location, 
made,  by  action  of  the  mining  laws  of  the  district,  a 
requisite  to  a  legal  title  to  the  location.  The  lateral 
branches  to  the  individual  mines  would  naturally  be 
built  by  the  mines  at  their  own  cost.  A  mine  opened 
by  tunnels  only  will  of  course  not  feel  the  necessity  of 
roads  so  promptly  and  keenly  as  one  which  is  com- 
pelled by  the  nature  of  the  ground  to  resort  at  once  to 
shaft-sinking,  as  the  former  will  be  able  to  get  along; 
with  packages  which  need  not  exceed  a  mule-load  in 
weight,  except  in  the  article  of  timber,  but  all  require 
the  roads  sooner  or  later  as  a  matter  of  economy  even 
in  provisions  and  supplies. 

PLANNING  REDUCTION  WORKS. — Having  then  become 
satisfied  that  the  ore  body  is  large  enough  and  rich 
enough  to  pay  for  its  extraction,  the  character  and 
size  of  the  reduction  works  remain  to  be  determined. 

Smelting. — Should  it  be  decided  that  the  ore  will  be 
best  reduced  by  smelting,  it  is  doubtful  whether  the 
mine  would  be  justified  in  erecting  its  own  works, 
unless  it  is  situated  where  purchases  of  various  other 
ores  can  be  readily  made  in  considerable  quantities,  as 
few  mines  produce  ore  which  may  not  be  worked  to 
greater  advantage  by  admixture  with  other  ores  which 
can  supply  its  deficiencies  without  adding  barren 


30  PROSPECTING  AND   VALUING  MINES. 

material  to  the  charge  in  the  furnace.  Ores  rich  in 
gold  and  silver,  but  poor  in  lead  (usually  called  "dry" 
ores),  may  require  rich  lead  ores  to  flux  properly ;  or 
ores  with  an  excess  of  silica  (quartz)  may  require  the 
addition  of  lime  or  iron-bearing  ores  to  accomplish  the 
same  result.  It  is  from  this  circumstance  that  the 
great  smelting  centers,  such  as  Denver,  Swansea,  etc., 
have  arisen,  which  purchase  everything  which  may  be 
offered,  and  mix  and  work  the  ores  to  the  best  advan- 
tage ;  each  class  of  ore  being  kept  separate  in  the  yard. 
A  furnace  charge  may  thus  be  made  up  from  four  or 
five  different  kinds  of  ore,  from  widely  separated  locali- 
ties, the  more  refractory  ores  being  added  in  small 
quantities  .to  those  which  work  more  readily. 

Concentration. — It  often  happens  in  a  vein  that  on 
one  of  the  walls  there  may  be  a  streak  of  solid  mineral 
suitable  for  shipment  as  it  comes  from  the  mine,  with 
no — or  only  slight — sorting,  while  the  balance  of  the 
vein  is  filled  with  material  in  which  there  is  so  much 
waste  as  to  render  this  impracticable;  or  the  entire 
vein  may  be  of  this  character. 

If  the  distance  from  the  mine  to  the  smelting  works 
is  great,  and  especially  if  any  considerable  portion  of 
it  be  only  trail  or  wagon  road,  it  may  not  pay  to  send 
these  poorer  ores,  as  the  whole  expense  including  trans- 
portation might  very  likely  more  than  equal  the  prod- 
uct. Such  ores  must  be  dressed  to  better  grade  by 
some  method  of  concentration  (usually  by  washing., 
more  rarely  by  air  or  magnetic  separators)  if  the  re- 
sulting concentrates  are  rich  enough  to  bear  the  cost 
of  transportation;  otherwise  they  may  be  valueless 
until  the  conditions  of  transportation  are  modified. 
Concentrates  consisting  largely  of  galena  or  heavy  sul- 
phuretted silver  ores  may  go  to  the  smelter,  but  those 
made  up  almost  entirely  of  iron  pyrites,  such  as  are 
obtained  from  many  gold  ores,  may  be  retained  at  the 
mine,  and  worked  by  chlorination,  if  the  daily  prod- 
uct be  large  enough  to  keep  a  small  reverberatory  fur- 


WHAT  CONSTITUTES  A  MINK.  31 

nace  for  roasting  in  steady  operation.  These  pyritous 
ores  may  also  be  made  into  a  commercial  product  by 
matte  smelting. 

The  capacity  of  the  concentrator  should  be  propor- 
tioned to  the  output  of  the  mine,  just  as  the  size  of  a 
stamp  mill  is  determined  by  the  same  factor,  and  this 
output  will  depend  on  the  size  of  the  ore  body  and  the 
condition  of  the  development. 

Ore  Supply  Needed.— -We  frequently  hear  of  a  mine 
being  ready  for  a  mill  when  it  has  nothing  more  than 
a  shaft  50  to  100  ft.  deep,  or  a  short  tunnel  on  the  vein. 
As  an  approximation  we  may  say  that  a  mine  should 
produce  1  ton  of  ore  daily  for  each  of  the  men  em- 
ployed around  it,  including  blacksmiths,  carpenters, 
carmen  and  outside  help.  There  are  of  course  mines 
where  better  than  this  is  done,  but  these  are  excep- 
tional. We  must  therefore  have  room  enough  in  the 
mine  for  a  considerable  number  of  men  to  be  engaged 
in  "stuping"  ore  and  this  involves  a  number  of  drifts 
or  stopes,  even  for  a  small  mill.  If  very  active  develop- 
ment is  going  on  and  the  ground  is  easily  worked, 
there  might  possibly  be  sufficient  ore  extracted  from 
the  face  of  the  various  headings,  sinkings  or  upraises 
to  keep  a  small  mill  going;  but  to  depend  on  these 
would  be  bad  policy,  for  the  ore  in  several  of  them 
might  "pinch"  at  the  same  time,  and  shut  the  mill 
down.  •  Indeed,  a  mill  should  not  be  built  until  the 
ore  body  has  been  so  thoroughly  explored  that  it  may 
be  perfectly  adapted  to  the  requirements,  both  as 
regards  size  and  character  of  equipment,  as  although 
it  may  be  possible  to  find  the  money  for  experiments 
or  mistakes,  they  must  all  ultimately  be  paid  for  by 
the  mine  and  diminish  the  profits. 

Calculation  of  Tonnage  Mined. — To  enable  the  pros- 
pector or  miner  to  form  a  quick  estimate  of  the 
amount  of  ore  which  he  may  be  extracting  daily  from 
a  drift,  the  following  table  will  be  found  useful. 
Three  kinds  of  ore  are  given  as  types.  First,  prac- 


PROSPECTING  AND   VALUING  MINES. 


ideally  clean  galena;  second,  a  concentrating  ore;  and 
third,  ordinary  gold  quartz  ore  or  free-milling  silver 
ore,  neither  of  which  carry  much  heavy  mineral. 
The  yield  in  pounds  is  for  1  running  foot  of  a  drift  7  ft. 
high,  and  this  figure  multiplied  by  the  number  of  feet 
run  daily  will  give  the  daily  yield  in  pounds,  provid- 
ing there  be  no  waste  in  saving  the  ore,  as  is  usually 
the  case  in  small  seams,  which  are  difficult  to  take  out 
clean,  especially  if  the  ore  is  brittle  or  friable. 

DAILY  ORE   EXTRACTION   PER   RUNNING   FOOT  J   DRIFT  7  FT. 
HIGH;  VEIN  VERTICAL. 


Class. 

Weight 
per  cubic 
foot. 

Thickness  of  Ore. 

3  in. 

6  in. 

9  in. 

1  ft. 

2  ft. 

3  ft. 

4ft 

1          

469 
'"328"' 

820 
0.41 
574 
0.29 
290 
0.16 

1641 
0.82 
1148 
0.57 
581. 
0.29 

2461 
1.23 
1722 
0.86 
871 
0  43 

3283 
1.64 
2296 
1.15 

11.62 
0.58 

6566 
3.28 
4592 
2.30 
2424 
1.16 

9849 
4.92 
9888 
3.44 
3486 
1.74 

13132  Ibs. 
6.56  tons 
9184  Ibs. 
4.59  tons 
4648  Ibs. 
2.32  tons 

1  

2 

2  

3 

166 

3          

The  principle  used  in  this  table  may  be  applied  also 
to  sinking  shafts,  thus:  multiply  the  area  of  the  work- 
ing face  (if  all  ore,  otherwise  the  area  of  ore  seam 
only)  by  the  number  of  feet  sunk  daily,  and  this  by 
the  weight  per  cubic  foot  in  the  table.  For  instance 
if  we  sink  3ft.  daily  on  a  2-ft.  vein  and  the  shaft  is  10 
ft.  long,  then  10  X  2  X  3  X  S28  =  60  cu-  ft-  X  328 
=  9.84  tons,  for  ore  of  the  second  class;  or  if  a  drift 
be  6  ft.  high  on  a  2-ft.  vein  and  we  run  2  ft.  daily,  we 
have  6  X  2  X  2  X  328  =  24  cu.  ft.  X  328  =  3.93  tons, 

To  assist  also  in  forming  an  estimate  of  the  most 
desirable  size  for  a  null,  the  next  table  will  be  found 
useful,  being  applicable  also  to  the  required  capacity 
of  a  concentrator. 

The  duty  of  a  stamp  varies  greatly  according  to  its 
weight,  the  height  of  the  drop  and  the  number  of 
drops  per  minute,  the  hardness  of  the  ore  to  be 


WHAT  CONSTITUTES  A  MINE. 


33 


crushed,  the  fineness  of  the  screen  through  which  the 
pulp  must  pass  to  escape  from  the  battery,  and  the 
height  of  the  discharge.  In  the  case  of  many  gold 
ores,  in  which  the  metal  is  very  fine  and  the  rock 
hard,  1|  tons  per  stamp  may  be  a  fair  day's  work  (24 
hrs.),  but  when  the  rock  is  softer,  or  the  gold  coarser, 
it  is  not  necessary  to  use  so  fine  a  mesh,  and  the  dut3T 
may  run  up  to  2  tons  daily ;  while  if  the  working  of 
the  ore  is  to  be  finished  by  grinding  in  pans,  or  the 
ore  is  exceedingly  soft,  a  mill  may  crush  still  coarser 
and  pass  2^  tons  or  over  under  each  stamp  in  24  hrs. 
The  table  is  therefore  arranged  for  each  of  those  three 
capacities,  and  shows  the  amount  of  ore  crushed  an- 
nually, its  contents  in  cubic  feet  and  the  area  of  the 
vein  which  would  be  extracted  at  various  thickness. 
It  is  based  on  the  ordinary  gold  quartz  or  free-milling 
silver  ores  (such  as  the  ores  of  the  Comstock),  and  13 
cu.  ft.  in  the  mine  are  considered  to  be  a  ton,  as  the 
result  of  determinations  made  on  that  lode;  and  300 
days  actual  running  time  in  the  year.  If  the  mill 
runs  more  steadily  the  quantities  must  be  proportion- 
ately increased. 

CAPACITY    OF    A    10-STAMP    MILL. 


Class  Ore 

£  ^ 
J,*1 

il 

Cubic  ft. 
per  ton. 

Equal  blk. 
Tons. 

Consumption 
per  diem, 

Consump.  per  annum 
(300  days.) 

tiN 

tons. 

2 

tons. 

2^ 
tons. 

titi 

tons. 

2 

tons. 

2^  tons. 

1  

165 

13.0 

1 

15 
195 
30 
195 

20 
260 
40 
260 

25 
325 
50 
325 

4,500 
58,500 
9,000 
58,500 

6,000 
78,000 
12,000 
78,000 

7,500  Tons. 
97,500  cu.ft. 
15,000  Tons. 
97,500  cu.ft. 

1 

2  

328 

6.5 

2 

2  

AKEA    OF    VEIN    EXTRACTED    ANNUALLY. 


Duty  of  Stamp. 

Vein,  1  ft. 

Vein,  2  ft. 

Vein,  3  ft. 

Vein,  4  ft. 

Tons. 
1U... 

Ft. 

585x100 

Ft. 
292x100 

Ft. 

195xiOO 

Ft. 
146x100 

22.:: 

780x100 

390x100 

260x100 

195x100 

2V, 

975x100 

488x100 

325x100 

244x100 

34  PROSPECTING  AND  VALUING  MINES. 

The  mixed  ore  is  merely  given  as  an  illustration. 
In  fact,  as  a  concentrating  ore,  it  would  more  likely 
be  treated  with  rolls  or  other  crushers  than  with 
stamps,  the  object  in  concentration  being  to  keep  the 
crushed  ore  in  as  large  grains  as  possible,  as  the  diffi- 
culties of  concentration  and  percentage  of  loss  increase 
with  the  fineness  of  the  pulp. 

The  table  itself  requires  but  little  comment.  While 
made  up  for  only  10-stamps  it  can  be  modified  to  apply 
to  any  desired  number — but  it  emphasizes  very 
strongly  the  desirability  of  long  ore  bodies,  as  it  is 
evident  that  to  get  a  year's  supply  from  a  tunnel  on  a 
vein  1  ft.  wide,  with  a  rise  of  the  surface  on  the  hill  of 
1  ft.  in  2,  we  should  have  to  follow  the  ore  484  ft. 
into  the  hill,  and  upwards  242  ft.  to  the  surface  at  the 
end  of  the  tunnel,  as  in  pi.  13,  fig.  9.  If  the  ore 
shoot  were  only  200  ft.  long  we  should  have  to  sink  on 
it  or  run  another  tunnel,  either  course  involving  an 
extra  amount  of  dead  work.  If  100  ft.  long  only,  we 
should  have  to  sink  585  ft.,  attaining  a  depth  of  nearly 
2,400  ft.  in  four  years.  If  200  ft.  long,  we  should 
sink  1,200  ft.  in  the  same  time.  As  the  cost  of  sink- 
ing and  working  m&in  shafts  is  the  heaviest  item  in 
mining,  the  length  of  the  shoot,  as  before  stated,  is  all 
important. 

Backs. — In  no  case  should  the  outcrop  be  consid- 
ered immediately  available  ore.  About  50  ft.  in 
depth,  or  at  any  rate  a  sufficient  thickness  to  avoid 
caving,  which  will  depend  on  the  width  of  the  vein 
and  the  condition  of  the  walls,  should  be  left  as  a  pro- 
tection to  the  mine  from  surface  water,  for  if  the  ore 
be  extracted  it  is  sure  to  leave  a  depression  into  which 
the  snow  and  rainfall  will  drain,  and  find  their  way  to 
the  lower  workings,  to  be  subsequently  pumped  out  at 
a  heavy  cost.  These  croppings  will  always  remain  an 
available  asset,  and  should  be  the  last  thing  taken  out 
of  the  mine. 

DEFINITION  OF  A  "MINE." — To  sum  up  then,  a  mine 


WHAT  CONSTITUTES  A  MINE.  35 

is  a  body  of  ore  of  sufficient  size  and  richness  to  repay 
all  costs  of  purchase  money,  erection  of  all  necessary 
plant,  dead  work,  extraction,  transportation  and  re- 
duction, with  good  interest  on  the  capital.  Success 
will  depend  largely  on  a  thorough  knowledge  of  the 
sizo  of  the  ore  body  as  regards  length,  depth  and 
thickness;  the  true  character  and  composition  of  the 
ore;  the  adaptability  of  the  hoisting  and  reduction 
works  to  the  requirements  of  the  property ;  careful 
management  by  thoroughly  competent  men  well  up  in 
the  business;  avoidance  of  mistakes  and  experiments, 
severe  pruning  of  all  unnecessary  expenses,  and  the 
treatment  of  the  mine  as  a  business  undertaking,  and 
not  as  a  gambling  proposition. 


CHAPTER  III. 
ROCK-FORMING  MINERALS  AND  ROCKS. 

IT  is  not  proposed  to  go  further  into  this  subject 
than  to  furnish  a  condensed  outline  of  the  composi- 
tion and  structure  of  the  principal  kinds  of  rocks, 
those  most  commonly  met  with  in  connection  with 
mineral  deposits,  so  that  the  prospector  may  be  able 
to  recognize  the  most  important  of  them.  To  describe 
all  the  different  varieties  would  require  a  volume,  and 
would  be  of  no  special  benefit  in  this  connection,  as 
the  distinctions  are  frequently  founded  on  the  pres- 
ence of  some  minerals  of  difficult  recognition  and 
quite  secondary  importance,  and  the  descriptions 
would  necessitate  a  much  more  extensive  knowledge 
of  mineralogy  to  make  them  intelligible  than  it  is 
necessary  for  a  miner  to  possess. 

ROCK-FORMING    MINERALS. 

The  principal  minerals  which  make  up  the  bulk  of 
the  rock  formations  are  very  few,  and  we  shall  find 
that  when  able  to  recognize  quartz  (or  silica),  feldspar, 
mica,  hornblende  and  angite,  there  will  not  be  much 
difficulty  in  giving  a  rock  a  name.  Some  of  these 
names  may  really  apply  to  groups  of  rocks,  but  in 
such  cases  the  name  of  the  group  will  be  close  enough. 
It  is  the  different  ways  in  which  these  five  minerals 
are  combined  that  distinguish  the  igneous  rocks  from 
each  other;  and  it  is  the  predominance  of  one  or  the 
other  in  the  secondarj'  rocks  (or  those  which  have  been 
made  out  of  the  wear  and  tear  of  the  igneous  series) 


ROCK-FORMING  MINERALS  AND  ROCKS.      37 

which  imparts  to  these  secondary  (or  sedimentary) 
rocks  their  peculiar  characters. 

Granite  consists  of  quartz,  feldspar  and  mica;  sye- 
nite, of  crystallized  fedspar  and  hornblende;  and 
basalt  of  feldspar  and  augite,  with  chrysolite  or  olivine, 
so  that  with  specimens  of  these  three  rocks  before  us, 
or  even  in  some  cases  with  granite  and  basalt  only,  we 
are  ready  to  study  the  characters  by  which  the  min- 
erals are  to  be  recognized.  The  basalt  used  for  refer- 
ence should  not  be  so  fine-grained  that  its  constituent 
minerals  are  indistinguishable  to  the  unassisted  eye. 

Quartz  is  the  glassy  portion  of  granite  which  cannot 
be  scratched  with  a  knife.  It  crystallizes  in  the  well- 
known  form,  the  separate  crystals  being  always  six- 
sided  prisms,  terminating  in  a  rather  blunt  pyramid 
with  six  sides  or  faces;  so  that  the  description  will  be: 
crystallizes  in  six-sided  prisms  (hexagonal)  with  six- 
sided  pyramid  for  a  termination;  color,  sometimes 
tinged  with  pale  smoky  or  rose  color,  sometimes  violet 
as  in  the  amethyst,  usually  colorless  and  transparent 
or  milky  white;  luster,  vitreous  (glassy);  hardness, 
cannot  be  scratched  with  a  knife,  and  itself  scratches 
feldspar,  glass,  etc.;  not  acted  on  by  sulphuric,  nitric 
or  hydrochloric  (muriatic)  acids. 

Feldspar  is  the  white  portion  of  granite  which  can 
be  scratched  with  a  knife.  There  are  numerous  varie- 
ties of  feldspar,  distinguished  by  their  having  either 
soda,  potash  or  lime  as  one  of  their  constituents  in 
addition  to  the  silica  and  alumina  which  are  the  essen- 
tial ingredients,  but  it  is  not  easy  to  give  differences 
which  would  be  easily  recognizable  by  the  beginner 
in  the  study.  The  crystallized  forms  are  usually 
white,  more  or  less  inclined  to  be  transparent  or  trans- 
lucent in  new  fractures,  but  often  weathering  to  a 
milky  white.  The  feldspars  in  granites  vary  in  color 
from  white  through  pink  to  dull  red,  and  often  occur 
as  seams  of  varying  width  running  through  the  body 
of  the  rock.  These  seams  are  inclined  to  break  into 


38  PROSPECTING  AND  VALUING  MINES. 

squarish  fragments,  showing  the  tendency  of  the 
crystals  of  this  variety  to  have  only  four  sides.-  In 
many  of  the  porphyries  almost  the  entire  mass  is 
feldspar,  the  body  of  the  rock  being  a  kind  of  paste 
of  uncrystallized  feldspar,  colored  various  shades  of 
brown,  green,  pink,  red,  and  purple,  with  scattered 
crystals  of  white  feldspar,  or  transparent  quartz,  im- 
bedded in  the  paste,  giving  to  it  a  spotted  look.  On 
decomposition  of  rocks  largely  composed  of  feldspar 
we  have  a  series  of  clay  formations,  just  as  granites 
yield  sand  and  sandstones. 

Mica  is  the  mineral  which  in  thin  plates  is  often 
wrongly  called  isinglass  (which  is  fish  glue).  In  color 
it  varies  from  colorless  or  white  to  black,  through 
various  shades  of  gray,  brown,  yellow,  green  and 
violet,  the  commonest  colors  being  white,  yellow,  dark 
brown,  dark  green  and  black.  While  sometimes 
found  in  crystals  of  large  size,  they  usually  are  quite 
small.  The  crystals  are  flat,  six-sided,  and  invariably 
split  into  extremely  thin  plates  parallel  to  the  base  of 
the  crystal.  When  broken  across  the  crystal,  as  is 
often  the  case  in  a  rock  fracture,  the  characteristic 
six-sided  form  may  not  be  visible,  but  the  thin  plates 
separate  easily  into  a  brushy  edge.  These  plates  are 
elastic  and  can  be  bent  considerably  without  break- 
ing, by  which  character  the  white  varieties  of  the  min- 
eral can  be  distinguished  from  the  crystallized  varieties 
of  gypsum,  which  are  also  white  and  transparent  and 
split  into  thin  plates  or  laminae,  but  are  brittle  and 
break  easily  on  bending.  They  are  also  destroyed  by 
the  action  of  heat,  whereas  mica  is  practically  infusi- 
ble at  ordinary  temperatures,  and  is  therefore  used  for 
stove  fronts,  etc.  When  a  rock  is  broken  the  crystals 
may  show  with  the  flat  side  up,  when  they  will  appear 
as  in  a,  pi.  13,  fig.  14,  but  if  the  fracture  cuts  through 
the  crystal  the  shape  may  be  like  b  in  the  same  figure, 
the  edges  of  the  thin  plates  showing  distinctly.  The 
colorless  or  white  mica  is  called  muscovite;  the  brown 
or  black  variety,  biotite. 


ROCK-FORMING  MINERALS  AND  ROCKS.        39 

Hornblende  occurs  usually  in  small  crystals,  gen- 
erally black  or  greenish  black.  It  is  harder  than  mica 
and  does  not  split  into  thin  layers,  which  fact  can  be 
determined  by  the  use  of  the  knife.  It  very  frequently 
crystallizes  in  little  square  columns  like  a  in  pi.  13, 
fig.  15,  and  sometimes  in  six-sided  crystals,  which 
may,  however,  be  easily  distinguished  from  mica  by 
having  two  of  the  opposite  sides  much  wider  than  the 
others,  as  in  6,  pi.  13,  fig.  15.  Hornblende  is  not 
always  crystallized.  It  often  occurs  in  greenish  or 
blackish  masses  with  a  fibrous  or  radiated  structure, 
sometimes  forming  a  rock  almost  by  itself  (horn- 
blende rock)  and  grades  down  into  asbestos,  which,  has 
practically  the  same  composition,  and  is  only  one  of 
the  uncrystallized  forms  of  hornblende,  of  which 
there  are  many  minor  varieties,  just  as  there  are  of 
mica. 

Augite  is  similar  in  appearance  to  hornblende, 
except  that  the  crystals  in  cross  section  show  eight 
sides,  as  in  pi.  13,  fig.  16,  and  is  much  less  important 
than  hornblende  to  the  student  of  rock  composition, 
until  he  has  made  some  progress.  We  have  thus 
two  usually  pale  or  white  minerals,  and  three  dark 
brown,  ^greenish  or  black  minerals  to  deal  with, 
and  a  very  small  amount  of  practice  will  enable 
anybod.y  to  pick  them  out  easily.  The  knife  will 
tell  the  difference  between  quartz  and  feldspar, 
'  but  mica,  hornblende  and  augite  are  easily  scratched 
with  the  knife,  giving  a  colorless  streak,  and  the  dif- 
ference between  the  three  minerals  must  be  determined 
by  the  shape  of  the  crystals. 

Many  other  minerals  are  associated  with  these,  as 
small  grains  of  magnetic  or  titanic  iron  in  granites, 
forming  the  "  black  sand"  of  the  miner;  but  they  are  not 
essential  constituents,  except  in  a  few  cases.  Garnets, 
tourmaline,  olivine,  chlorite,  chrysolite  and  apatite, 
the  last  four  all  green  minerals,  may  occur  in  small 
grains  or  crystals,  or  may  sometimes  be  so  abundant 


40  PROSPECTING  AND  VALUING  MINES. 

as  to  give  a  distinct  character  to  the  rock,  which  may 
then  be  called  a  "garnet  rock,"  "chloritic  slate/ 'etc., 
as  we  shall  notice  later  on. 

KOCK    STRUCTURE. 

All  rocks  present  lines  of  fracture,  even  though  they 
were  deposited  as  a  solid  mass,  but  some  present  a 
series  of  parallel  planes  along  which  they  split  with 
great  facility,  sometimes  along  the  lines  of  original 
deposit,  and  sometimes  nearly  at  right  angles  to  the 
former.  These  fissure  lines  are  known  as  stratification 
or  lamination,  cleavage  and  bedding  planes,  and  it  is 
highly  important  that  they  should  not  be  confounded. 

Stratification  is  the  result  of  earthy  matter  being 
deposited  in  water  as  layer  after  layer,  with  intervals 
of  time  between  the  deposition  of  the  layers,  during 
which  the  first  layer  deposited  had  time  to  harden  or 
form  a  sort  of  crust  which  prevented  it  mixing  freely 
with  the  succeeding  layer  and  so  on;  so  that  the  mass 
has  become  like  a  series  of  sheets  of  paper  laid  one  upon 
the  other,  and  when  converted  into  rock  by  the  lapse 
of  time,  and  raised  out  of  the  water,  the  rocks  split 
easily  along  these  lines  of  deposit.  The  layers  may 
vary  greatly  in  thickness,  depending  on  the  amount  of 
sediment  brought  down  by  the  stream  and  the  length 
of  the  flood  periods.  It  is  easy  to  understand  that  a 
stream  during  flood  will  carry  immense  quantities  of 
matter  into  a  lake  or  the  ocean,  becoming  clear  during 
periods  of  drought,  thus  fulfilling  the  conditions  called 
for;  and  that  such  streams  as  the  Mississippi,  Amazon 
and  Ganges  may  form  beds  of  vast  extent,  while  others 
may  be  limited  to  the  area  of  a  small  lake.  Eocks 
formed  in  this  manner  are  known  as  sedimentary  or 
stratified  rocks. 

Cleavage. — Certain  rocks,  such  as  roofing  slates, 
while  belonging  to  the  stratified  series,  have  become 
so  altered  by  pressure  that  they  no  longer  split  along 
the  lines  of  stratification  or  deposit,  sometimes  known 


ROCK-FORMING  MINERALS  AND  ROCKS.        41 

as  "lamination  lines"  (a  term  applied  to  the  thinner 
strata),  but  on  a  series  of  joints  which  have  been  sub- 
sequently formed  by  this  pressure,  generally  more  or 
less  at  right  angles  to  the  lines  of  the  original  deposit. 
The  old  lines  of  lamination  are  obliterated,  and  this 
new  series  of  joints  is  much  more  numerous  than  the 
original  horizontal  planes,  and  the  splitting  character 
much  more  perfect,  dividing  the  rock  into  very  thin 
sheets.  This  structure  is  known  as  "cleavage. "  It  is 
more  or  less  developed  in  coal  beds  and  is  there  known 
as  the  * 'cleat,"  and  is  the  cause  of  the  coal  breaking 
into  small  pieces  when  mined.  In  crystals  of  minerals 
the  cleavage  is  the  line  on  which  the  mineral  splits 
most  readibr,  and  is  usually  parallel  to  one  of  the 
smooth  faces  (facets)  of  the  crystals.  This  is  well 
illustrated  in  mica  and  gypsum. 

Bedding  Planes  and  Strike  Joints. — In  addition  to 
these  splitting  planes,  all  rocks  (even  limestone  and 
eruptive  rocks)  have  acquired  two  or  three  sets  of 
joints,  more  or  less  at  right  angles  to  each  other, 
which  divide  the  mass  into  large  blocks  and  greatly 
facilitate  the  labor  of  thequarryrnan,  who  takes  advan- 
tage of  them  in  his  mining  operations.  These  may  be 
altogether  independent  of  stratification,  being  the 
result  of  the  upheaval  and  compression  of  the  earth's 
crust,  though  in  some  cases  they  may  follow  some  of 
the  more  or  less  horizontal  lines.  Upon  their  char- 
acter frequently  depends  the  shape  of  mineral  veins 
and  deposits.  The  joints  which  are  roughly  hori- 
zontal, or  parallel  to  the  original  stratification,  are 
called  "bedding  planes"  or  "dip  joints,"  and  the 
series  running  with  the  general  trend  of  the  rocks 
through  the  country,  the  "strike  joints."  These 
joints  may  be  very  numerous  or  wide  apart,  and  are 
the  cleanest  cut  in  close  fine-grained  rocks  such  as 
limestones,  where  they  are  not  obscured  by  the  stratifi- 
cation planes,  and  also  in  some  granites,  furnishing 
fragments  of  all  sorts  of  angles.  These  joints  may  be 


42  PROSPECTING  AND   VALUING  MINES. 

only  a  few  yards  long,  or  may  extend  for  a  mile,  the 
latter  feature  being  most  prominent  in  close-grained 
rocks  which  have  suffered  comparatively  little  dis- 
turbance. A  little  thought  will  show  why  building 
stones  should  be  put  into  the  structure  in  the  same 
position  that  they  had  in  the  quarry,  that  is,  laid  ac- 
cording to  their  " bedding,"  being  stronger  in  this  way 
than  any  other  and  less  liable  to  scale  off,  on  exposure 
to  frosts  and  the  acids  in  the  rain  water  of  cities. 

Metamorphixm.  — All  rocks  are  constantly  changing 
their  character.  The  mud  banks  of  to-day  will  be  the 
shales  and  slates  of  the  far  future,  and  our  sand  banks, 
the  sandstones  of  a  coming  era.  In  the  same  way  and 
by  the  same  agencies  of  time,  moisture,  pressure 
and  heat,  many  of  the  older  sedimentary  rocks  have 
lost  much  of  their  original  character.  The  sand- 
stones have  become  massive  quartzites,  in  which 
the  small  grains  of  quartz  which  compose  the  sand- 
stone are  no  longer  visible;  and  the  slates  and  shales 
have  lost  many  of  their  lines  of  stratification, 
besides  suffering  other  changes  which  have  imparted 
to  them  a  new  common  character,  known  as 
"schistose. "  Such  rocks  are  called  schists.  It  is 
sometimes  a  very  hard  matter  in  a  hand  specimen  of 
these  rocks  to  determine  by  the  eye  whether  it  belongs 
to  the  metamorphic  or  eruptive  series,  so  extensive  have 
been  the  changes,  and  only  the  microscope,  or  a  dis- 
tant view,  when  the  main  features  of  the  mass  alone 
strike  the  eye,  can  settle  the  question.  (When  the 
microscope  is  used  in  the  determination  of  the  rocks,  a 
flake  of  rock  is  ground  down  so  fine  that  print  can  be 
read  through  it,  and  it  is  this  film  that  under  the 
microscope  tells  the  story  of  its  origin  and  composi- 
tion). By  reference  to  pi.  2,  fig.  3,  the  difference  be- 
tween the  structure  of  slates  and  schists  will  be  better 
understood*  The  upper  part  of  the  figure  represents 
a  slate  rock  (let  us  say  one  in  which  there  are  numer- 
ous fragments  of  hornblende  by  way  of  illustration, 


UOCK-FORMING  MINERALS  AND  ROCKS.        43 

otherwise  a  hornblende  slate)  and  the  lower  part  a 
schist  having  the  same  composition,  called  a  horn- 
blende schist.  In  the  latter  there  has  been  such  are- 
arrangement  of  the  particles  that  though  the  mass 
retains  some  traces  of  stratification,  in  the  parallelism 
of  its  bedding  planes,  it  has  lost  the  smooth  lamination 
planes,  and  consists  of  a  series  of  plates,  thickest  in 
the  middle  and  thinning  out  all  round  like  a  flat  lens, 
the  result  being  a  very  characteristic  appearance 
(known  as  "foliated''),  in  which  only  a  few  of  the 
lines  of  stratification  have  been  preserved,  although 
the  process  has  not  been  such  as  to  produce  clean-cut 
cleavage.  The  result  has  in  most  cases  been  to 
toughen  the  rock,  felting  the  constituents  together, 
and  few  are  more  difficult  to  handle  than  this  same 
hornblende  schist,  as  it  will  not  split  and  is  much  less 
brittle  than  most  eruptive  rocks.  In  these  metamor- 
phic  groups  the  changes  have  usually  been  so  great 
that  all  traces  of  fossils  have  been  destroyed,  and  their 
geologic  age  can  only  be  inferred  from  their  associa- 
tions. They  are  abundant  in  volcanic  regions  and 
largely  associated  with  mineral  deposits.  Their  ulti- 
mate condition  when  metamorphism  is  complete,  ap- 
pears to  be  a  return  to  a  rock  in  which  all  trace  of  its 
sedimentary  origin  has  disappeared  and  which  cannot 
be  distinguished  from  those  which  we  know  to  have 
had  an  eruptive  origin.  The  term  metamorphism  is 
not  applied  to  the  simple  hardening  of  muds  into 
slates,  or  similar  processes,  but  only  to  those  changes 
in  which  a  rearrangement  of  the  particles  has  pro- 
duced a  rock  with  a  decidedly  differing  appearance. 

CLASSIFICATION    OF    HOCKS. 

Rocks  may  be  divided  into  simple  and  compound, 
the  first  class  including  those  which  consist  essentially 
of  one  mineral,  such  as  some  limestones,  gypsum,  rock 
salt,  and  serpentine;  the  second  including  those  which 
are  made  up  of  a  combination  of  several  dissimilar 
minerals. 


44  PROSPECTING  AND  VALUING  MINES. 

The  simple  rocks  resolve  themselves  into  two  groups, 
the  first  of  which  consists  of  chemical  precipitates,  and 
the  second  of  organic  structures. 

The  compound  rocks  resolve  themselves  into  what 
may  be  called  the  "original"  group,  consisting  of 
those  of  eruptive  or  volcanic  origin,  which  are  again 
divided  into  the  "plutonic"  and  "igneous"  series,  the 
former  term  being  applied  to  those  rocks  which  have 
been  intruded  from  below  without  reaching  the  sur- 
face, and  the  latter  to  those  which  have  been  ejected 
as  lava  from  volcanic  vents;  and  the  "secondary" 
group,  which  is  made  up  of  rocks  derived  from  the 
wear  and  tear  of  all  other  rocks  previously  formed, 
whether  original  or  already  secondary.  This  group 
may  be  divided  into  the  "stratified"  rocks  which  have 
been  deposited  in  layers  by  the  action  of  water,  and 
those  which  are  the  result  of  volcanic  outbursts  other 
than  lava,  and  which  may  be  termed  "fragmentary." 

The  stratified  rocks  are  again  devisible  into  the 
simple  and  metamorphic  sections. 

The  boundary  lines  between  all  these  groups  are  very 
poorly  defined,  and  they  can  only  be  taken  as  gener- 
alizations. Thus  many  limestones  may  contain  so 
much  sand  and  clay,  along  with  their  fragments  of 
coral  and  sea  shells,  as  to  be  almost  a  compound  rock, 
but  they  largely  lack  the  stratified  character,  while  in 
the  compound  rocks  many  which  have  been  ejected 
from  volcanoes  also  occur  in  situations  where  they 
have  obviously  never  been  exposed  to  the  atmosphere 
at  the  time  of  their  formation,  as  the  basalts  in  the 
coal  beds.  The  following  tabular  presentation  will 
show  the  general  arrangement  in  a  compact  form : 

BOCKS    CLASSED    ACCORDING    TO    ORIGIN. 

A.    SIMPLE  ROCKS. 

I.    Chemical  Deposits— such   as   some  limestones,    rock-salt,   gypsum, 

serpentine. 

II.    Organic  Deposits— such  as  some  limestones,  chalk,  infusorial-earth, 
coal,  etc. 


ROCK-FORMING  MINERALS  AND  ROCKS.         45 

B.    COMPOUND  ROCKS. 
I.     Original  group: 

1.  Plutonic  series — such  as  granite,  syenite,  etc. 

2.  Igneous  series— such  as  basalt,  trachyte,  etc. 
II.    Secondary  group: 

1.    Stratified  Rocks: 

a.  Simple — such  as  shales,  sandstones  and  conglomerates. 

b.  Metamorphic— such  as  quartzite,  soapstone,  schists,  etc. 
8.    Fragmentary  Rocks— such  as  breccias,  volcanic  tufas,  and 

glacial  deposits. 

SIMPLE  BOOKS. — As  the  limestones  fall  within  the 
limits  of  both  the  divisions  of  this  class  no  attempt 
will  be  made  to  treat  the  sections  separately.  Rock 
salt  and  coal  are  very  important  commercially,  but  the 
lime  rocks  from  the  great  bulk  of  this  series,  either  as 
sulphates  (gypsum)  or,  more  commonly,  as  carbonates 
(limestone,  calcite).  The  great  mass  of  limestone 
has  been  segregated  from  sea  water,  into  which  it  has 
been  carried  by  the  streams  which  have  dissolved  it 
from  the  rocks  through  which  their  waters  have  per- 
colated. 

Limestones  proper  vary  in  hardness  from  very  soft 
to  quite  hard  rocks,  compact  and  usually  close-grained 
in  structure,  ranging  in  color  from  white  through 
shades  of  yellow  and  drab,  to  blue  and  even  black,  and 
consist  essentially  of  carbonate  of  lime,  which  effer- 
vesces on  the  application  of  acids;  and  they  may  con- 
tain so  many  impurities,  such  as  clay,  sand,  etc.,  that 
they  become  unsuitable  for  the  manufacture  of  quick- 
lime for  building  purposes.  This  arises  from  the 
varying  conditions  under  which  they  have  been 
formed,  and  which  determine  their  character.  A  large 
portion  of  them  consist  of  the  rocky  skeletons  of  corals 
or  the  shells  of  minute  animalcules. 

Chalk  consists  of  the  minute  shells  of  a  vast  group 
of  small  animals  called  Foraminifera,  which  live  in 
sea  water  in  countless  millions.  These  extract  the 
carbonate  of  lime,  which  forms  their  shells,  from  the 
sea  water,  and  when  dead  they  fall  to  the  bottom 
forming  a  soft  ooze,  which  if  exposed  to  view  in  future 
ages  would  be  the  same  as  chalk  as  we  know  it.  These 


46  PROSPECTING  AND   VALUING  MINES. 

shells  are  so  minute  that  only  a  powerful  microscope 
can  show  their  forms,  and  it  takes  millions  of  them  to 
form  a  cubic  inch  of  rock.  The  purer  forms  of  chalk 
are  soft,  white  and  earthy,  but  time  has  wrought  such 
changes  that  some  of  its  varieties  become  more  and 
more  compact,  until  they  grade  into  limestones,  and 
the  organic  formations  have  had  their  constituents  so 
modified  that  nearly  all  trace  of  their  organic  origin 
has  disappeared,  and  they  can  scarcely  be  distin- 
guished from  the  granular  crystalline  chemical 
deposits. 

Flint,  which  is  a  form  of  silica,  occurs  in  the  chalk 
beds,  and  has  probably  been  formed  by  the  separation 
of  small  quantities  of  silica  from  some  of  the  organic 
remains,  by  percolating  waters,  and  its  concentration 
into  rough  nodules  of  very  compc^ct  structure,  usually 
dark  or  blackish  in  color,  and  resembling  horn  or 
glass  in  thin  fragments. 

Coralline  Limestones. — Immense  deposits  of  lime- 
stona  have  been  built  up  by  coral  insects,  like  the  reefs 
so  common  in  the  warmer  seas  of  the  world  at  present, 
and  these  usually  contain  numerous  fossils  which  stand 
out  more  or  less  prominently  on  the  surfaces  of  the 
rock  which  have  been  weathered  by  the  action  of  air 
and  water,  though  they  may  be  indistinguishable  on  a 
freshly  broken  surface.  This  probably  arises  fom  the 
greater  solubility  of  the  uncrystallized  portions  of  the 
rock. 

Other  deposits  have  been  made  up  of  broken  frag- 
ments of  coral  detached  from  the  main  reef,  and 
washed  upon  the  adjacent  beach,  where  they  have 
been  mixed  with  sand  and  broken  sea  shells,forming 
beds  with  many  impurities. 

Besides  these,  there  are  compact  beds  which  appear 
to  have  been  chemically  deposited.  To  this  section 
also  belong  those  deposits  made  by  hot  springs  which 
deposit  the  excess  of  lime  held  in  solution  on  cooling 
as  "sinter,"  a  term  applied  to  all  such  formations, 


ROCK-FORMING  MINERALS  AND  ROCKS.         ^ 

whether  formed  of  lime  or  silica.  If  made  of  the 
former,  they  are  known  as  <( calcareous  sinter/'  if  of 
the  latter  as  "silicious  sinter." 

Limestones  for  making  quicklime  should  be  free 
from  silica.  When  this  is  present  in  considerable 
quantities,  it  not  infrequently  makes  itself  visible  on 
the  weathered  surfaces,  imparting  to  them  a  peculiar 
dry  harsh  feel,  the  lime  wearing  away  more  rapidly 
than  the  silicious  portion,  which  is  thus  left  in  relief 
on  the  exposed  surfaces.  These  silicious  limestones 
and  those  carrying  clay  or  alumina,  which  are  not 
suitable  for  the  production  of  ordinary  lime,  are  util- 
ized in  the  manufacture  of  hydraulic  cements. 

Marble  is  a  variety  of  limestone  in  which  the  entire 
mass  has  become  highly  crystalline.  The  finest  varie- 
ties are  as  clear  and  even  in  grain  as  lump  sugar.  In 
colors  there  is  an  infinite  variety,  many  kinds  being 
often  found  in  the  same  belt.  Freedom  from  iron  min- 
erals (which  will  rust  and  stain  the  dressed  slabs), 
purity  of  color  and  closeness  of  grain  are  the  chief 
elements  in  determining  the  value  of  marble,  but  cheap 
transportation  to  market  is  essential  to  the  successful 
opening  of  a  quarry,  however  good  the  stone  may  be. 

Dolomite  is  a  magn-esian  limestone,  consisting  of  the 
carbonates  of  lime  and  magnesia,  usually  of  a  crystal- 
ine  texture  and  yellowish  tints ;  and  while  some  bodies 
appear  to  be  original  chemical  precipitates,  others  are 
undoubtedly  ordinary  limestones  which  have  been 
changed  by  the  percolation  of  magnesian  waters. 
Both  the  ordinary  carbonate  ol  lime  and  the  magne- 
sian variety  are  used  as  fiuxes  in  the  smelting  of  iron 
and  lead,  but  all  limestones  are  not  of  equal  value  for 
this  purpose,  any  more  than  they  are  for  quicklime. 
A  chemical  analysis  or  practical  test  must  determine 
their  value  for  both  purposes. 

Magnesite  in  composed  of  carbonate  of  magnesia, 
and  is  much  less  common  than  limestone  or  dolomite. 

Limestone  crystals  (calcite,  calcspar)  are  often  mis- 


48  PROSPECTING  AND  VALUING  MINES. 

taken  for  quartz,  and  as  it  is  a  frequent  accompani- 
ment of  metallic  ores,  the  chief  differences  are  worth 
noting.  In  crystallized  limestone  the  characteristic 
shape  is  rhomboidal ;  that  is,  the  crystals  are  four- 
sided,  but  none  of  the  angles  are  right  angles,  while 
each  pair  of  sides  is  parallel.  When  crystallized  in 
pointed  forms  with  six  sides,  the  crystals  are  like 
pyramids,  without  the  straight  portion  seen  in  quartz, 
and  the  apex  is  more  pointed.  This  sharp-pointed 
character  has  given  it  the  name  of  "dogtooth  spar. " 
In  addition  to  these  differences  it  is  much  softer  than 
quartz,  being  easily  scratched  by  the  knife,  and  splits 
easily  along  the  line  of  cleavage.  Carbonate  of  lime 
(calcite)  is  not  likely  to  be  mistaken  for  any  other 
mineral  than  quartz  except  feldspar  and  gypsum,  and 
from  these  it  may  be  distinguished  by  the  action  of 
acids,  or  by  the  fire  test  to  ascertain  if  it  will  form 
quicklime.  This  will  set  slowly,  whereas  burnt 
gypsum  forms  plaster  of  paris  and  sets  promptly  when 
mixed  with  water,  but  does  not  become  as  hard  as  the 
cements  made  by  calcining  silicions  limestones. 

Gypsum  (sulphate  of  lime)  differs  from  the  carbo- 
nate in  that  it  does  not  effervesce  with  acids.  It  is 
valuable  chiefly  as  the  source  of  plaster  of  paris  and  as 
a  manure,  the  latter  consisting  simply  of  the  raw  pul- 
verized rock.  Gypsum  crystallizes  in  white  translu- 
cent masses  which  scratch  very  easily  and  split  into 
thin  non-elastic  flakes,  which  may  sometimes  be  ob- 
tained of  great  size;  this  form  is  known  as 

Selinite. — Fibrous,  very  silky  varieties  of  gypsum 
are  known  as  "satin  spar;"  and  the  close-grained 
forms,  when  of  even  texture  and  finely  crystalline,  are 
distinguished  as  "alabaster," 

Infusorial  earth  resembles  chalk  in  appearance  and 
general  constitution,  being  made  up  of  the  skeletons 
or  shells  of  minute  organisms,  but  the  term  is  gener- 
ally applied  to  those  which  consist  of  the  scales  of 
little  vegetable  organisms  called  "diatoms."  These 


ROCK-FORMING  MINERALS  AND  ROGK8.        49 

are  made  of  silica  instead  of  lime,  and  consequently 
the  rock  is  not  acted  on  by  acids.  The  excessive  fine- 
ness of  the  powder  derived  from  crushing  these  earths, 
and  the  hardness  of  the  individual  particles,  make 
them  very  useful  for  polishing  powders,  which  are 
known  commercially  as  "tripoli,"  "electro  silicon," 
etc. 

Serpentine  is  essentially  a  hydrated  silicate  of  mag- 
nesia, and  is  a  dark  blackish-green  rock,  with  very 
smooth  slippery  joints,  generally  highly  polished  and 
variegated  with  greenish  or  yellowish  films,  like  soap- 
stone  or  French  chalk  such  as  is  used  by  tailors.  The 
more  brilliantly  colored  varieties  are  used  for  orna- 
mental stonework,  under  the  French  name  of  "verde 
antique."  While. some  serpentines  have  been  original 
deposits  on  the  sea  floor,  others  have  been  in  all  prob- 
ability intruded  masses  of  eruptive  rock,  containing 
olivine,  which  have  undergone  extensive  metamor- 
phism  and  assumed  their  present  aspect. 

COMPOUND  BOCKS,  ORIGINAL  GROUP. — Instead  of  de- 
scribing these  rocks  under  the  two  series  named  in 
the  table,  which  is  based  on  their  origin,  and  often 
calls  for  extended  investigation  to  determine  to  which 
series  any  particular  rock  should  be  referred,  it  will 
be  sufficient  to  here  classify  them  by  some  striking 
physical  peculiarity  which  is  easily  recognizable  by 
everybody. 

Three  distinct  forms  may  be  recognized:  (1)  Those 
which  are  entirely  crystalline,  or  made  up  of  a  mass  of 
crystals  each  of  which  is  distinct;  (2)  those  in  which 
a  certain  portion  of  the  crystals  are  scattered  through 
a  "paste"  of  feldspar,  which  is  very  compact  and  does 
not  show  any  distinct  structure;  and  (%)  those  which 
do  not  show  any  signs  of  crystallization,  but  are  of  the 
same  character  throughout. 

It  must  be  understood  that  this  arrangement  is 
purely  arbitrary,  as  it  separates  closely  allied  forms; 
but  it  possesses  the  great  advantage  of  being  appli- 


50  PROSPECTING  AND   VALUING  MINES. 

cable  without  the  use  of  the  microscope,  which  is  es- 
sential to  any  scientific  classification.  In  this  place 
the  object  is  simply  to  enable  the  miner  to  find  out 
the  approximate  name  of  any  particular  rock  with  the 
smallest  amount  of  trouble,  and  not  to  educate  him 
for  an  expert  petrologist.  Only  the  most  characteris- 
tic of  these  rocks  will  be  described. 

In  the  crystalline  rocks  the  size  of  the  crystals  does 
not  change  the  name  of  the  rock.  The  size  of  the 
crystals  may  be  said  to  merely  indicate  the  rate  at 
which  the  mass  of  rock  cooled,  and  the  amount  of  pres- 
sure under  which  the  cooling  took  place.  If  an 
ejected  lava  cools  very  rapidly  there  is  no  time  for  the 
particles  to  arrange  themselves  in  any  particular  man- 
ner, and  the  product  is  a  rock  which  has  all  the  ap- 
pearance of  the  slag  from  a  smelting  furnace.  If  the 
rate  of  cooling  has  been  slower  we  have  a  crystalline 
rock  in  which  the  separate  crystals  are  small;  and  if 
the  cooling  has  been  excessively  slow  we  may  have 
large  and  well-defined  crystals,  there  having  been 
ample  time  for  a  complete  arrangement  of  all  the  con- 
tents of  the  rock  into  their  respective  kinds,  according 
to  the  proportions  of  the  various  constituents  and 
their  relative  affinities.  "While  this  may  be  stated  as  a 
general  proposition,  it  must  not  be  taken  as  an  abso- 
lute rule,  as  it  may  be  varied  by  the  more  or  less  easy 
fusibility  of  the  different  minerals  varying  the  proc- 
ess. These  rocks  vary  greatly  in  their  mode  of  forma- 
tion, though  they  all  agree  in  their  comparatively 
deep-seated  origin.  As  they  are  intimately  connected 
with  the  great  changes  in  the  earth's  crust,  and  prob- 
ably owe  their  fusion  to  the  heat  developed  by  the 
immense  pressure  and  friction  incident  to  these 
changes  (and  perhaps  by  chemical  action),  it  is  not 
surprising  that  we  find  them  chiefly  in  those  localities 
where  these  changes  are  most  activebr  at  work,  namely 
in  the  great  mountain  ranges.  They  may  be  found  as 
great  bosses  or  as  dikes  which  have  been  squeezed  into 


-HOCK-FORMING  MINERALS  AND  ROCKS.        51 

the  rocks  from  below  while  in  a  plastic  or  semi-fluid 
condition,  as  in  the  case  of  some  granites  (pi.  5,  fig. 
5)  or  of  the  trachytes  shown  in  pi.  5,  figs.  1,  2  and  4. 
In  the  latter  case  the  force  exerted  was  not  sufficient 
to  break  through  the  crust  of  overlying  rock,  but  was 
sufficient  to  lift  a  portion  of  the  surface  into  the  form 
of  a  dome,  the  space  thus  formed  being  filled  with  the 
molten  rock,  a  portion  of  which  through  smaller  vents 
found  its  way  in  the  horizontal  layers  of  the  sedi- 
mentary rock,  forming  beds  between  them,  just  as  the 
basalt  lava  has  found  its  way  into  coal  seams,  as 
shown  in  pi.  5,  fig.  6,  and  between  the  shales  as  in  pi. 
5,  fig.  3.  In  these  figures  No.  4  shows  the  theoretical 
structure  of  such  a  lava  mass,  showing  the  pipe  a 
through  which  the  lava  (black)  was  seeking  an  outlet, 
and  the  lava  forming  a  solid  mass  with  branches  pene- 
trating the  overlying  strata,  and  forming  thin  beds 
between  them.  In  fig.  1  we  have  the  top  of  such  a 
mass  exposed  in  the  side  of  a  canon,  of  which  a  b  is 
the  bed,  with  the  strata  (partially  worn  away)  curving 
over  the  solid  lava;  while  in  fig.  2  we  have  an  actual 
cross  section  through  a  mountain  formed  out  of  such 
a  block,  the  solid  lines  showing  what  remains  in  place, 
and  the  dotted  lines  the  original  shape  of  the  portion 
which  has  been  removed,  a  being  the  bed  on  which  the 
lava  (black)  spreads  out,  and  b  the  shales,  between 
the  layers  of  which  thin  sheets  of  lava  found  a  lodg- 
ment, as  shown  by  the  alternating  outcrop  of  c,  c.  In 
'fig.  3  we  have  similar  horizontal  beds  of  lava  c,  pene- 
trating the  strata  as  offshoots  from  the  dike  d,  but  the 
lava  at  c  is  evidently  only  the  remains  of  a  similar 
sheet  from  which  the  superincumbent  strata  have  been 
worn  away,  and  not  an  outflow  in  the  open  air,  because 
remains  of  other  lava  sheets  are  found  above  other 
strata  at  higher  levels,  as  at  e.  In  fig.  6,  a,  a,  are 
shales,  b  coal,  and  c  basalt,  the  latter  intruded  into 
the  coal  bed  through  the  dikes  d,  d.  In  this  case  the 
coal  is  destroyed  and  the  lava,  originally  black,  has 


52          PROSPECTING  AND  VALUING  MINES. 

been  altered  to  a  whitish  rock  by  the  action  of  the 
coal  on  the  cooling  lava. 

In  other  cases  the  lava  has  forced  its  way  to  the  sur- 
face, through  the  fissured  rocks,  and  overflowed  from 
the  dike  in  immense  sheets,  or  has  been  ejected  from 
volcanic  cones  in  huge  streams,  which  have  traveled 
many  miles,  filling  up  valleys  and  even  continuing 
their  course  under  the  sea.  Similar  eruptions  take 
place  on  the  sea  floor.  Volcanic  eruptions  are  also  fre- 
quently accompanied  by  the  formation  of  vast  fissures 
on  the  flanks  of  the  mountain  which  become  filled  with 
lava,  and  all  these  exhibitions  of  deep-seated  heat  pro- 
duce profound  changes  in  the  rocks  which  they 
traverse,  the  heat  of  lava  streams  being  preserved  for 
many  years  after  all  volcanic  activity  has  ceased,  so 
slowly  do  they  cool  when  once  crusted  over. 

It  is  thus  evident  that  the  same  body  of  lava  may 
cool  under  very  different  conditions,  and  these  have 
more  or  less  effect  on  the  appearance  of  the  rock,  so  that 
the  determination  of  the  different  kinds  is  often  a 
matter  of  difficulty  even  to  experts. 

ORIGINAL  COMPOUND  ROCKS,  FIRST  GROUP  (wholly 
crystalline). — Adopting  the  simplest  though  arbitrary 
classification  for  the  sake  of  convenience,  and  disre- 
garding for  the  present  purpose  differences  of  origin, 
the  compound  "original"  rocks  (including  both  plu- 
tonic  and  eruptive  rocks)  of  the  first  group  embrace 
such  species  as  granite,  syenite,  felsite,  elvanite, 
trachyte,  basalt,  etc. 

Granite  is  a  mixture  of  quartz,  feldspar  and  mica. 
It  may  be  either  fine-grained  or  coarse,  and  vary  in 
color  according  to  the  color  of  some  one  of  its  constit- 
uents. If  the  mica  is  white,  we  have  a  nearly  white 
or  light-colored  granite;  pink  and  red  granites  take 
their  color  and  names  from  the  tint  of  the  feldspar, 
just  as  very  dark  or  even  black  granite  results  from 
the  abundance  of  black  mica.  When  the  feldspar  is 
white  and  mica  black  in  moderate  quantities  we  have 


HOCK-FORMING  MINERALS  AND  ROCKS.        53 

various  tints  of  gray.  It  is  often  traversed  by  dikes 
of  younger  age,  usually  paler  in  color  and  more  com- 
pact than  the  rock  which  they  cut;  and  though  called 
the  oldest  rock,  it  is  frequently  found  as  veins  (con- 
nected with  the  main  mass)  which  penetrate  both  the 
stratified  and  unstratified  rocks  above  it  (as  shown  in 
pi. -5,  fig.  5),  which  are  usually  much  altered  thereby. 
Granite  belongs  to  the  group  of  rocks  called  "plu- 
tonic,"  which  have  not  broken  through  the  surface  of 
the  earth's  crust,  but  have  consolidated  at  some  depth 
beneath  it.  Sometimes  hornblende  is  present  in  small 
quantities  along  with  the  mica,  when  it  may  be  termed 
hornblendic  granite,  on  the  principle  of  using  as  a 
descriptive  adjective  the  name  of  any  peculiar  mineral 
present  in  a  rock  but  not  essential  to  its  composition. 

Granite  seems  to  be  the  underlying  rock  of  the 
entire  series,  and  if  this  be  the  case  it  is  not  strange 
that  all  the  rocks  which  have  been  derived  from  it 
should  show  a  tendency  to  return  to  it,  in  appearance 
and  composition,  during  the  lapse  of  time,  through 
the  agencies  of  heat  and  pressure. 

Felsite,  felsite-porphyry  and  elvanite  are  crystalline 
mixtures  of  quartz  and  feldspar,  usually  so  intimately 
mixed  that  in  felsite  the  crystallization  is  scarcely  vis- 
ible, while  elvanite  is  more  distinctly  granular.  The 
latter  rock  is  of  frequent  occurrence  in  the  mining  dis- 
tricts of  Cornwall,  and  the  dikes  of  it  are  known  by 
the  miners  as"elvans,"  from  which  term  the  scientific 
name  of  the  rock  has  been  derived. 

Trachyte  and  Rhyolite.  — In  many  respects  trachyte 
resembles  granite,  but  may  be  easily  separated  by  the 
feel  of  a  fresh  fracture,  which  is  exceedingly  sharp  and 
rough,  suggesting  the  surface  of  a  cat's  tongue.  It 
occurs  as  dikes  and  large  eruptive  overflows,  belong- 
ing to  the  series  of  modern  lavas.  In  color  the  rock 
has  a  wide  range  of  variation  from  gray  to  pink  and 
brown.  In  composition  the  feldspar  predominates 
over  the  quartz  and  is  usually  accompanied  by  horn- 


54  PROSPECTING  AND  VALUING  MINES, 

blende,  mica  or  augite.  It  may  be  considered  the 
modern  equivalent  of  the  older  granite,  but  differing 
from  the  latter  in  being  a  volcanic  product.  Ehyolite 
is  another  rock  so  closely  related  to  trachyte  that  the 
beginner  will  find  it  hard  to  separate  them.  As  the 
mode  of  occurrence  and  general  associations  are 
entirely  similar  to  trachytes,  the  distinction  is  not  of 
essential  consequence0 

Syenite, — The  foregoing  rocks  have  quartz  as  an 
essential  constituent,  while  in  syenite  and  basalt  it  is 
absent  as  free  or  visible  quartz,  or  nearly  so.  For- 
merly syenite  was  considered  a  crystalline  mixture  of 
quartz,  feldspar  and  hornblende,  but  the  term  is  now 
used  for  a  rock  made  up  of  crystalline  feldspar  and 
hornblende,  with  mica  as  an  accessory  or  accidental 
mineral.  In  appearance  it  strongly  resembles  granite 
(but  the  knife  will  show  the  absence  of  quartz),  and 
occurs  in  much  the  same  way.  The  feldspar  has  a 
different  composition  from  that  found  in  granite. 

Basalt  is  the  last  of  the  wholly  crystalline  series 
which  need  be  noticed  here.  It  is  usually  a  very  dark, 
blackish,  fine-grained  rock,  consisting  of  feldspar  and 
augite,  with  a  variety  of  associated  minerals,  such  as 
olivine,  occurring  as  small  olive-green  grains,  of  which 
the  oxides  of  iron  and  manganese  form  about  15%  of 
the  mass,  making  the  rock  unusually  heavy  (sp.  gr., 
2.95).  It  has  been  ejected  from  modern  volcanoes  in 
immense  quantities,  covering  hundreds  of  square 
miles  in  the  States  of  Washington  and  Oregon,  the  suc- 
cessive eruptions  or  overflows  from  dikes  forming  a 
series  of  layers,  resembling  strata,  and  having  in  the 
aggregate  an  immense  thickness.  It  is  also  the  rock 
now  being  ejected  by  the  volcanoes  in  the  Hawaiian 
Islands,  and,  from  its  fluid  character  when  molten, 
forms  perfect  rivers.  It  was  such  lava  streams  which 
filled  the  mountain-valleys  of  California  and  covered 
the  gold-bearing  gravels  during  the  second  outbreak, 
as  the  trachytes  had  previously  done  at  a  much  earlier 


ROCK-FORMING  MINERALS  AND  ROCKS.        55 

period.  When  cooled  rapidly,  as  on  the  surface  of  a 
new  outbreak,  it  becomes  full  of  bubbles  formed  by 
the  expansion  of  the  steam  contained  in  the  lava  (to 
which  it  owes  its  fluidity),  and  it  is  in  these  cavities 
that  opals,  calcite  and  similar  minerals  have  been 
formed  by  percolating  waters.  The  porous  lavas,  with 
the  bubbles  so  filled,  are  known  as  amygdaloids  (from 
a  word  meaning  almond).  Below  the  surface  the  pres- 
sure has  prevented  the  expansion  of  the  steam  so  per- 
fectly, so  that  the  bubbles  get  smaller  and  smaller  till 
the  mass  becomes  perfectly  crystalline.  Very  fluid 
lavas  may  be  so  filled  with  these  air,  gas,  or  steam 
cavities  that  they  look  spongy  and  will  float  on  water 
as  "pumice  stone, "  or  they  may  be  drawn  out  by  the 
violent  winds  eddying  round  the  crater  into  fine 
threads  like  spun  glass,  in  which  form  they  are  known 
as  "Pele's  hair, "  Pele  being  a  goddess  associated  with 
the  Hawaiian  volcanoes.  Basalt  frequently  crystallizes 
into  a  columnar  structure,  the  pillars  being  five  or  six- 
sided,  with  ball-and-socket  joints.  This  columnar 
structure  is  always  at  right  angles  to  the  sheet  of  lava, 
so  that  in  dikes  they  form  more  or  less  horizontally  from 
wall  to  wall,  and  in  overflows  more  perpendicularly. 

SECOND  GROUP  (porphyritic). — In  this  group  we 
have  quartz-porphyrjr  and  a  whole  series  of  other  por- 
phyries in  which  visible  quartz ^is  absent  and  which 
for  the  purposes  of  the  miner  we  may  designate  simply 
as  '"porphyry,"  using  the  term  as  a  general  one. 

Quartz-porphyry  or  dacite  consists  of  a  paste  of 
feldspar  which  shows  no  sign  of  crystalline  structure, 
the  color  of  which  may  range  from  dirty  white  to  pink, 
purple,  brown  or  slate-graj'.  In  this  paste  are  scat- 
tered small  grains  of  transparent  quartz,  making  a 
very  characteristic  rock  which  occurs  in  large  masses, 
the  rock  belonging  to  the  series  of  old  lavas.  It  is 
largely  developed  in  the  Comstock  mining  region. 

Porphyry. — Under  this  head  may  be  classed  all  the 
rocks  in  which  the  paste  just  described  contains  dis- 


56  PROSPECTING  AND  VALUING  MINES. 

tinct  crystals  of  feldspar,  giving  them  a  spotted  appear- 
ance. They  may  contain  mica,  hornblende  or  augite 
as  an  additional  mineral,  and  it  is  the  presence  of 
these,alorig  with  differences  in  the  composition  of  the 
feldspars,  which  constitutes  the  basis  for  a  new  name. 

They  occur  as  dikes,  veins,  intruded  sheets,  or  as 
surface  deposits,  and  include  such  species  as  porphy- 
rite,  diorite  or  greenstone,  andesite,  phonolite  or 
clinkstone,  etc. 

THIRD  GROUP  (non-crystalline). — In  this  group  we 
have  pumice  stone,  already  described,  and  as  the  prin- 
cipal rock — 

Obsidian,  which  is  a  lava  cooled  very  rapidly,  look- 
ing like  coarse  bottle  glass,  and  hence  frequently 
called  ''volcanic  glass/'  It  is  of  various  shades  in 
greenish  black,  black  or  red,  and  the  red  varieties  are 
sometimes  marbled  with  black  streaks  which  are  drawn 
out  in  the  direction  of  the  flow  of  the  lava  stream 
while  3'et  in  a  pasty  condition. 

It  is  not  pretended  that  the  foregoing  descriptions 
are  absolutely  scientific.  To  lead  the  miner  into  the 
mysteries  of  orthoclase,  plagioclase  and  triclinic  feld- 
spar would  be  to  hopelessly  bewilder  him ;  yet  many 
of  the  distinctions  between  the  various  eruptive  and 
intrusive  rocks  are  based  on  the  one  or  other  of  these 
feldspars  being  the  predominant  component.  The  use 
of  a  powerful  microscope  is  often  necessary  to  settle 
disputed  questions,  and  all  rock-students  know  how 
many  of  these  there  are.  If  the  descriptions  will 
enable  a  person  to  distinguish  a  granite  from  a  por- 
phyry, a  felsite  from  a  basalt,  or  a  trachyte  from  a 
quartz-porphyry,  they  will  serve  their  purpose;  in- 
deed, they  would  almost  do  so  if  they  will  separate  an 
eruptive  or  volcanic  rock  from  a  schist,  and  a  schist 
from  a  shale.  The  student  who  once  begins  to  take  an 
interest  in  rocks  will  soon  discover  that  their  varieties 
are  almost  infinite,  but  that  they  resolve  themselves 
into  a  few  tolerably  well  defined  groups,  and  will  in- 


ROCK-WORMING  MINERALS  AND  HOCKS.        57 

evitably  be  led  to  examine  into  their  differences  and 
perpetually  to  ask  himself  the  reason  why.  When  the 
eye  is -thus  trained  it  is  time  enough  to  name  these 
slighter  differences,  which  are  puzzling  enough  to 
expert  observers. 

A  general  term  for  many  of  these  eruptive  rocks  is 
"trap,"  from  a  Scandinavian  word  meaning  steps  or 
stairs,  in  allusion  to  the  forms  in  which  they  often 
"weather."  This  weathering,  a  term  applied  also  to 
the  changes  which  take  place  on  the  surface  of  rocks 
exposed  to  the  destructive  action  of  the  elements,  is 
sometimes  of  great  assistance  in  determining  the 
true  character  of  the  rock,  especially  in  those  with  a 
fine  grain  and  dark  color,  as  the  feldspar  on  exposure, 
instead  of  retaining  the  glassy  look  which  it  may  have 
in  the  mass  (making  it  hard  to  recognize),  becomes 
milky  white  and  shows  distinctly  on  the  surface  of  the 
bowlders,  even  though  in  a  clean  new  fracture  the 
latter  may  be  nearly  uniform  dark  bluish-gray  or 
almost  black.  In  other  cases  the  outer  surface  may  be 
pitted  with  little  angular  holes  from  which  the  crystals 
have  been  dissolved,  thus  readily  separating  the  rock 
from  the  stratified  series  to  which  it  may  otherwise 
have  much  resemblance.  If  depending  on  the  pitted 
surface,  however,  care  must  be  taken  to  ascertain  that 
the  pits  are  not  "casts"  of  crystals  of  iron  pyrite,  as 
this  mineral  is  abundant  in  all  rocks  whether  eruptive 
or  stratified,  especially  so  in  the  former  when  decompo- 
sition of  the  mica  or  hornblende  has  set  in. 

SECONDAKY  COMPOUND  BOCKS,  STRATIFIED  SERIES. — The 
character  of  the  rocks  which  are  in  process  of  decay 
and  are  being  swept  into  the  smaller  streams  and 
thence  through  the  rivers  to  the  ocean,  plays  an  im- 
portant part  in  the  formation  of  soils  and  the  sedi- 
ments carried  away  by  water  and  deposited  to  form 
rocks.  If  granite  were  the  only  rock  being  worn  away 
by  a  stream,  and  the  disintegration  were  complete,  we 
should  have  clean  deposits  of  sand  and  clay  full  of 


58 


PROSPECTING  AND  VALUING  MTNE8. 


mica  and  hornblende.  But  when  the  stream  began 
to  cut  into  other  rocks  there  would  ensue  a  change  in 
the  character  of  the  deposits,  which  would  become 
yet  more  strongly  marked  if  the  destruction  of  the 
rocks  had  extended  into  groups  already  stratified.  It 
is,  therefore,  easy  to  see  that  the  conditions  surround- 
ing the  format! jn  of  stratified  rocks  are  very  complex, 
and  we  must  look  for  great  local  differences  even  in 
rocks  made  at  the  same  geologic  period.  So  great  is 
this  difference  at  times  that  it  would  be  impossible  to 
place  many  rocks  in  their  right  chronological  order  if 
it  were  not  for  the  fossil  remains  with  which  they 
abound,  so  that  the  prospector  should  religiously  pre- 
serve all  such  fossils  as  he  may  find,  or  take  such  a 
note  of  the  locality  that  he  may  direct  others  to  it. 

The  ultimate  analysis  of  the  foregoing  compound 
original  rocks  gives  approximately  the  percentages 
shown  in  the  following  table,  compiled  from  Geikie, 
from  which  it  will  be  seen  that  they  resolve  them- 
selves into  three  groups  chemically.  The  large  per- 
centage of  iron  and  manganese  in  the  porphyries  and 
basalt  is  largely  due  to  the  presence  of  grains  of  mag- 
netic iron  in  the  porphyries,  and  the  oxides  of  iron 
and  manganese  in  the  basalt. 

CHEMICAL  COMPOSITION  OF  ORIGINAL  COMPOUND  ROCKS. 


Silica. 

Alumina  . 

Lime. 

Iron,  Man- 
ganese, etc. 

Potash. 

Soda. 

Magnesia 

Granite. 

% 

72 

% 

15 

% 

1  6 

% 

2  2 

5  1 

2  8 

0*3 

Quartzite  
Syenite  

77 
60 

13 

17 

0.7 
4  4 

1.1 
7.0 

4.3 
6.6 

0.7 
2.4 

1.0 
2.6 

Trachyte  
Porphyries  .  .  . 
Basalt  

60 
53 
45 

17 
16 
15 

3.5 
6.3 
10.5 

8.0 
14.0 
15.0 

5.0 
1.3 
1  5 

4.0 
2.2 
3  5 

1.0 
6.0 

6  5 

The  potash,  soda  and  magnesia,  being  soluble,  are 
carried  away  on  decomposition,  and  form  the  alkaline 
matter  which  accumulates  in  lakes  without  outlets, 


ROCK-FORMING  MINERALS  AND  ROCKS.         59 

such  as  Walker,  Mono,  Pyramid,  and  other  lakes  in 
the  Great  Basin  between  the  Sierra  Nevada  and  Rocky 
Mountain  ranges  in  the  United  States,  giving  them 
their  intensely  saline  character  if  the  rocks  furnishing 
the  material  contain  but  little  magnesia,  and  a  bitter 
taste  if  there  be  much  of  the  latter  present.  Thus  the 
drainage  of  a  basalt  region  should  furnish  magnesian, 
and  of  a  trachyte  country  saline  waters. 

The  silica,  alumina,  lime  and  iron  are  thus  left  to 
form  the  sedimentary  rocks.  The  iron  plays  its  part 
chiefly  as  a  component  of  the  clays  and  a  cementing 
material  for  the  sandstones,  to  be  afterward  leached 
out  and  accumulated  in  local  deposits  as  bog  iron, 
which  by  the  changes  of  time  becomes  the  source  of 
other  iron  deposits  of  various  kinds.  The  lime,  being 
less  soluble  than  the  alkalies,  is  slowly  leached  out  of 
some  of  the  rocks,  especially  by  water  containing  car- 
bonic acid,  and  redeposited  on  exposure  to  the  air  as 
a  sediment  by  the  springs  which  have  dissolved  it,  or 
is  carried  to  the  ocean  to  furnish  material  for  the 
coralline  structures  or  the  shells  of  its  multitudinous 
life. 

The  guartz  and  clay,  the  chief  constituents  left,  fur- 
nish the  bulk  of  the  sedimentary  material,  which,  with 
the  addition  of  waterworn  fragments  of  undecomposed 
rock  naturally  resolves  the  deposits  into  two  series,  to 
the  first  of  which  belong  the  conglomerates,  gravels 
and  sands,  and  to  the  second  the  muds  and  clays 
(derived  chiefly  from  the  alumina),  shales  and  slates. 

All  material  washed  into  a  stream  by  the  rainfall  on 
the  adjacent  hills,  and  falling  therein  by  the  under- 
mining action  of  the  current  on  the  banks,  becomes  a 
source  of  sedimentary  deposits.  If  the  fragments  are 
too  large  to  be  moved  by  the  current,  they  remain  in 
the  stream  bed  until  gradually  worn  away  by  the  attri- 
tion of  smaller  rocks  and  sand  over  them ;  if  smaller 
and  movable,  they  are  only  carried  along  to  the  first 
dead  water,  whether  it  be  a  lake  or  the  ocean,  and  thero 


60  PROSPECTING  AND  VALUING  MINES. 

deposited,  and  this  deposition  involves  a  sorting  of 
the  material.  The  larger  and  heavier  pieces  will  be 
deposited  first  as  coarse  gravel,  then  finer  gravel,  then 
sand,  and  the  finest  sediment  being  carried  the  fur- 
thest will  be  laid  down  as  mud  or  silt,  unless  the  lake 
be  so  small  and  the  current  of  the  stream  so  swift  that 
it  is  swept  into  the  outlet  beyond,  leaving  only  a  deposit 
of  sand  and  gravel.  It  will  thus  be  seen  that  the  same 
material  may  appear  as  gravel  at  one  place,  sand  at 
another,  and  mud  at  another.  But  large  streams 
usually  carry  only  the  finer  sediments  when  they  reach 
comparatively  level  country,  having  left  the  larger 
particles  at  the  foot  of  the  mountain  slopes,  and  as  in 
the  case  of  the  Amazon  they  may  spread  this  over  a 
sea  bottom  hundreds  of  square  miles  in  extent.  A 
similar  process  is  carried  on  at  the  sea  beaches  where 
the  reflux  of  the  tide  may  carry  the  finer  material  sea- 
ward, leaving  the  coarser  at  the  foot  of  the  bluffs. 

While  stratification  usually  occurs  horizontally,  it 
is  not  necessarily  so,  as  in  the  case  of  mountain 
streams  the  coarse  gravel  would  accumulate  the  most 
rapidly,  forming  a  sloping  bank,  on  which  the  layers 
deposited  in  successive  flood  times  would  take  the 
same  inclination.  So,  in  like  manner,  the  ashes 
ejected  from  volcanic  cones,  falling  on  the  sloping 
sides  of  the  same,  would  accumulate  in  layer  after 
layer,  presenting  all  the  appearance  of  deposits  made 
in  water,  but  retaining  the  slopes  of  the  flanks  of  the 
cone. 

Conglomerates  are  largely  formed  on  sea  beaches  by 
the  rolling  of  the  rocks  washed  out  of  the  shore  bluffs 
into  rounded  fragments,  which  will  naturally  be  of 
various  kinds  of  rock,  according  to  the  material  of  the 
hills  which  are  being  worn  away.  Deposits  formed  by 
river  action  are  apt,  from  the  circumstances  under 
which  they  are  formed,  to  be  much  more  limited  in 
extent  than  those  made  along  shore  lines.  They  con- 
sist of  rounded  pieces  of  rock  of  various  kinds 


ROCK-FORMlAls  MINERALS  AND  ROCKS.        61 

cemented  together  either  with  hardened  clay  or  silica, 
and  sometimes  with  iron  oxides  derived  from  percolat- 
ing waters  or  the  black  sand.  They  may  be  fairly 
fine  if  made  of  gravel,  or  excessively  coarse,  and,  if 
made  up  chiefly  of  one  rock,  may  be  known  by  the 
name  of  that  if  it  is  specially  desired  to  distinguish 
and  separate  them,  as  quartz-conglomerate,  or 
trachyte-conglomerate  such  as  is  found  in  connection 
with  the  lavas  of  the  California  gold-gravel  channels. 
Some  of  the  schists  contain  bowlders,  leading  to  the 
conclusion  that  they  are,  in  this  case,  merely  altered  or 
metamorphic  conglomerates;  and  in  other  cases  the 
cementing  process  is  so  perfect  and  the  consolidation 
of  the  mass  so  complete  that  the  pebbles  will  break  in 
two  on  a  general  line  of  fracture,  without  becoming 
removed  from  the  mass.  Cuttings  through  conglom- 
erate beds  stand  with  nearly  vertical  walls. 

Sandstones  consist  essentially  of  sand  cemented  to- 
gether with  iron,  each  grain  being  coated  with  a  thin 
film  of  iron  oxide,  which  imparts  the  general  color  to 
the  mass,  as  in  the  red  sandstones.  The  grains  of 
sand  when  cleaned  of  the  coating  may  be  either  tinted 
or  colorless.  Mica  forms  a  common  addition  to  many 
sandstones,  as  well  as  lime  and  clay,  when  they  may 
be  distinguished  as  mica-sandstone,  etc.  The  lime 
and  clay  are  not  readily  discernible  to  the  unaided 
eye.  Flagstones  are  only  sandstones  which  split  easily 
into  thin  slabs,  suitable  for  sidewalks.  Buhrstones 
are  sandstones  so  thoroughly  cemented  that  they  are 
very  hard  and  rough  enough  to  furnish  the  grinding 
surface  required  in  millstones.  "Freestone"  is  some- 
times a  sandstone  which  cuts  freely  in  any  direction, 
either  with  the  stratification  or  across  it,  but  hardens 
on  exposure  to  the  air.  The  term  is  however  some- 
times applied  to  limestones  and  other  rocks  which 
present  the  same  characteristics. 

Quartzite  is  a  sandstone  which  has  been  subjected 
to  the  action  of  heated  waters,  which  have  aggregated 


62  PROSPECTING  AND  VALUING  MINES. 

the  grains  of  sand  together  with  a  silicious  cement, 
probably  derived  from  a  partial  solution  of  the  grains 
of  sand  themselves,  until  the  rock  has  lost  its  granular 
structure,  and  to  a  large  extent  resembles  massive 
quartz.  It  is  a  common  rock  in  mining  regions,  and 
occurs  with  other  metamorphic  rocks,  but  also  in  situ- 
ations where  the  associated  strata  have  undergone  no 
change. 

Clays  are  formed  out  of  the  alumina  in  the  feldspar 
and  other  minerals,  silica  excepted,  of  the  eruptive  or 
volcanic  rocks,  and  are  the  finest  of  the  sediment  car- 
ried in  suspension  by  water,  varying  in  color  and  com- 
position according  to  the  rock  to  which  they  owe  their 
origin,  and  the  particular  stage  in  the  journey  of  the 
stream  at  which  they  were  deposited.  They  may  be 
exceedingly  pure,  in  which  case  they  are  called  "fat" 
in  the  language  of  the  brickmaker  and  potter,  and 
from  this  range  downward  to  a  clay  loam,  in  which 
there  may  be  a  very  large  excess  of  impurities,  of 
which  iron  forms  a  large  part.  The  richer  clays 
require  the  addition  of  sand  to  make  good  brick,  but 
possess  the  advantage  of  a  more  uniform  composition, 
which  enables  the  manufacturer  to  regulate  the  addi- 
tion of  sand  to  a  nicety  and  thus  produce  an  article  of 
uniform  quality;  the  poorer  kinds  make  only  the  most 
inferior  grades. 

Fireclay. — A  good  fireclay  has  a  composition  of 
silica  73.82%,  alumina  15.88%,  oxide  of  iron  2.95%, 
water  6.45,  with  traces  only  of  lime,  sulphur,  mag- 
nesia, soda  and  potash,  which  is  very  nearly  the 
chemical  composition  of  granite,  with  the  lime,  potash, 
soda,  and  magnesia  eliminated,  so  that  such  clays 
could  easily  be  formed  by  the  decomposition  of  that 
rock.  Fireclay  is  largely  associated  with  coal  seams, 
the  clay  floor  retaining  the  waters  which  made  the 
tangled  swamps  in  which  many  coal  beds  were  prob- 
ably formed. 

Kaolin  or  porcelain  clay  is  derived  from  the  decom- 


ROCK-FORMING  MINERALS  AND  ROCKS.         63 

position  of  the  feldspars  of  the  granitic  rocks  and  por- 
phyries, and  is  essentially  a  compound  of  the  oxides  of 
silicon  and  aluminum  mixed  with  water,  the  composi- 
tion when  pure  being  silica  46.3%,  alumina  39.8%, 
water  13.9%.  Impurities  are  frequently  present,  the 
principal  one  being  iron  derived  from  the  other  min- 
erals present  in  the  rock  from  which  it  was  formed. 
When  pure  it  is  white,  ranging  through  yellowish  to 
brownish  red,  when  much  iron  is  present,  say  5%  or 
upward.  The  preparation  of  the  clay  by  grinding, 
washing  and  settling  is  a  slow  and  tedious  process. 

Shales  are  only  hardened  clays  which  have  been  de- 
posited from  time  to  time  in  thin  sheets,  so  that  the 
resulting  mass  splits  readily  into  thin  layers  along  the 
lines  of  deposit;  but  while  they  all  retain  this  common 
character,  they  vary  greatly  in  composition,  and  may 
be  distinguished  from  each  other  by  the  names  of  the 
minerals  which  may  give  a  special  appearance  to  the 
rock,  as  mica-shale,  hornblende-shale,  silicious  shale 
(when  sandy)  or  simply  clay-shale.  In  color  they  vary 
as  much  as  in  composition,  from  pale  gray  to  black  ;  in 
the  latter  case  they  are  usualbr  colored  by  small  scales 
of  graphite — black-lead  or  plumbago — derived  from 
the  carbon  of  the  organic  matter  washed  down  with 
the  clay  sediment  and  buried  with  it.  This  organic 
matter  may  be  so  abundant  that  the  shales  may  be 
called  bituminous  or  oil-shales. 

Slates. — For  all  this  series  of  rocks  the  term  slate 
is  also  very  generally  used,  as  clay-slate,  mica-slate, 
etc. ;  but,  strictly  speaking,  the  term  slate  is  applied 
only  to  those  rocks  which  have  lost  their  shaly  char- 
acter by  end  pressure  cm  the  strata,  and  now  split  on  the 
lines  of  cleavage,  as  previously  defined,  such  as  roof- 
ing slate  (pi.  12,  fig.  4).  In  these  latter  rocks  the 
particles  have  rearranged  themselves  at  right  angles  to 
the  line  of  pressure.  This  effect  has  been  repeatedly 
produced  exprimentally,  and  the  student  must  early 
relinquish  the  common  idea  of  the  absolute  rigidity  of 


64  PROSPECTING  AND  VALUING  MINES. 

rocks.  As  a  matter  of  fact,  they  are  plastic  or  may  be 
molded  to  an  extraordinary  degree,  many  of  the  shales 
and  slates  having  been  folded  and  wrinkled  like  sheets 
of  paper,  and  this  not  only  on  a  grand  scale,  but  down 
to  the  most  minute  plications.  Samples  of  this  fold- 
ing are  shown  in  pi.  12,  fig.  8,  where  the  folding 
element  has  been  the  intrusion  of  the  dike  d;  and  in 
pi.  4,  fig.  6,  where  the  cause  has  been  general  lateral 
pressure,  crowding  the  rocks  into  a  smaller  amount  of 
space  horizontally.  Not  only  can  cold  lead  under  a  suffi- 
cient pressure  be  squeezed  as  a  jet  through  an  aperture 
suitably  provided,  but  cold  iron  can  also  be  pressed  so 
as  to  penetrate  into  the  angles  of  suitable  molds.  This 
facility  with  which  rocks  can  be  modified  in  their 
structure,  and  bent  and  folded,  has  an  important  in- 
fluence on  the  filling  of  veins,  as  intense  heat  is 
developed  in  the  process,  and  this,  in  the  presence  of 
water,  will  decompose  and  rearrange  all  the  compo- 
nents of  the  rock,  dissolving  some  which  are  replaced 
by  new  combinations  and  producing  metamorphism. 

SECONDARY  GROUP,  METAMORPHIC  SERIES. — All  the 
shales  and  slates  may  be  thus  converted  into  schists, 
previously  described.  As  in  the  case  of  the  shales, 
each  variety  may  be  distinguished  by  the  predominat- 
ing or  characteristic  mineral,  as  mica-schist,  which 
gradually  shades  off  into  gneiss,  which  is  a  rock  hav- 
ing a  composition  exactly  like  granite,  but  without 
the  uniform  crystalline  character  of  the  latter,  or  the 
foliated  structure  of  the  schists.  In  gneiss  there  is  a 
tendency  for  all  the  mica  to  be  laid  in  horizontal  or 
more  strictly  speaking  parallel  lines,  while  the  quartz 
may  occur  in  pure  bands,  and  there  is  a  tendency  of 
the  mass  when  viewed  on  the  large  scale  to  look  like  a 
coarsely  stratified  rock.  From  this  characteristic  ap- 
pearance there  may  be  a  gradual  change  until  it  is 
hard  to  say  whether  the  rock  should  be  called  gneiss 
or  granite,  leading  us  to  the  conclusion  that  many  so- 
called  granites  are  only  the  last  stage  of  the  metamor- 


ROCK-FORMING  MINERALS  AND  ROCKS.        65 

phisrn  of  an  original  sandy  bed  of  clay  containing 
mica,  such  as  are  common  everywhere. 

When  hornblende  is  the  chief  mineral,  we  have 
hornblende-schist,  a  tough,  dark  greenish  rock,  which 
shales  off  into  a  rock  so  essentially  composed  of  horn- 
blende that  it  loses  the  schistose  character  and  be- 
comes what  is  called  hornblende  rock.  When  the 
shading  off  is  in  the  direction  of  a  more  crystalline 
structure,  the  gradations  may  be  toward  a  hornblende- 
gneiss,  and  from  that  to  syenite,  just  as  the  mica  schists 
grade  into  granites.  It  will,  of  course,  be  understood 
that  these  changes  are  not  to  be  seen  in  small  speci- 
mens, but  only  in  the  large  area  of  a  mountain  range. 

When  the  metamorphism  has  proceeded  so  far  that 
the  micas  have  been  decomposed,  so  as  to  liberate  the 
magnesia  by  the  absorption  of  water,  we  have  a  series 
of  rocks  all  of  which  are  characterized  by  a  smooth, 
slippery,  greasy  feel  to  the  touch,  commencing  with 
talcose  schists,  of  a  greenish  or  yellowish  tint;  inclin- 
ing to  reddish  from  the  decomposition  of  the  minerals 
containing  iron.  On  further  change  we  may  have 
asbestos,  forming  in  the  seams  and  joints  of  the  rock, 
or  the  whole  mass  may  be  converted  into  soapstone, 
which  is  a  compact  whitish  or  greenish  rock,  without 
pronounced  crystalline  structure,  easily  cut  by  the 
knife  or  turned  in  a  lathe.  From  its  infusibility  and 
the  facilit3r  with  winch  it  can  be  cut  into  suitable 
blocks,  soapstone  forms  an  excellent  lining  for  fur- 
naces which  are  subjected  to  intense  heat. 

Chlorite-schists  are  similar  in  composition  to 
talcose  schists,  but  the  talc  is  replaced  by  an  apple- 
green  mineral  called  chlorite,  which  not  infrequently 
occurs  along  with  quartz  in  mineral  veins,  as  on  the 
mother  loile  in  California  and  elsewhere. 

This  series  of  rock  3  may  be  thus  summed  up,  on  two 
lines  of  progressive  alteration,  according  to  the  start- 
ing point: 

(1)  Sands,  sandstones,  quartzite;  (2)  muds,  clays, 
shales,  schists,  gneiss,  syenite  or  granite. 


66  PROSPECTING  AND  VALUING  MINES. 

SECONDARY  GROUP,  FRAGMENTAL  SERIES. — Besides  the 
rocks  previousl3T  described,  all  of  which  show  evidence 
of  deposition  in  water  and  something  like  a  regular 
order,  there  are  still  a  few  which  cannot  strictly  be 
classed  with  them.  These  are  either  volcanic  or  glacial. 

Volcanic  Products. — Yolcanic  outbursts  are  often 
accompanied  by  the  discharge  of  enormous  quantities 
of  dry  dust  and  stones,  some  of  which  are  rounded  and 
others  angular,  or  the  dust  may  be  an  impalpable 
powder.  Some  of  these  may  have  been  deposited 
under  water,  when  they  naturally  have  a  distinct  strat- 
ification; while  in  those  laid  down  in  the  open  air 
this  structure  may  not  be  so  well  defined,  though  the 
alternating  character  of  the  material  ejected  may  have 
formed  apparently  stratified  layers  on  the  sides  of  quite 
steep  mountain  cones.  The  discharges  may  consist 
entirely  of  lava  fragments,  or  may  include  pieces  of  all 
the  rocks  traversed  by  the  volcanic  vent,  and  in  many 
cases  they  have  been  cemented  together  by  a  lava 
paste.  The  various  conditions  in  which  they  are 
found  suggest  appropriate  names,  as  volcanic  con- 
glomerate, where  the  pebbles  and  bowlders  are 
rounded;  volcanic  breccia,  where  these  are  angu- 
lar; volcanic  agglomerate,  where  there  is  a  mixture  of 
the  two  foregoing,  usually  without  any  distinct  strati- 
fication. The  finer  materials  are  called  tufas  or  tuffs 
and  as  a  rule  are  distinctly  stratified ;  and  while  of 
volcanic  origin  may  contain  organic  remains  or  fos- 
sils, equally  with  ordinary  water-formed  sediments. 
The  term  lapilli  is  applied  to  the  coarser  portion  of 
the  volcanic  dust,  so  largely  ejected  prior  to  the  ap- 
pearance of  lava  at  many  volcanic  vents,  to  distinguish 
it  from  the  finer  volcanic  ash,  which  may  be  a  powder 
so  fine  that  it  can  be  carried  hundreds  of  miles  by  the 
wind  before  finding  a  final  restin  *  place.  This  finest 
ash  forms  a  large  part  of  the  sediment  brought  up  from 
the  floor  of  the  deep  sea,  where  it  gathers  as  slowly 
and  silently  as  dust  in  a  deserted  room. 


ROCK-FORMING  MINERALS  AND  ROCKS.        67 

Glacial  Products. — While  all  the  material  dis- 
charged by  glaciers  into  running  streams  is  undistin- 
guishable  from  other  sedimentary  deposits,  those 
dropped  by  melting  ice  present  only  faint  traces  of 
sedimentation  or  none  at  all.  Where  floating  ice  is 
dropping  its  load  of  earth,  sand,  gravel,  rounded 
bowlders  and  angular  fragments,  on  the  top  of  strata 
which  are  forming  under  the  surface  of  lakes  or  shal- 
low seas,  we  may  find  immense  bowlders  or  bunches  of 
gravel  irregularly  mixed  with  such  deposits,  which, 
while  they  betray  the  condition  of  the  climate  at  the 
period  of  their  formation,  do  not  justify  any  special 
name  to  such  accumulations  of  sediment.  But  where 
the  glacial  deposits  are  laid  down  by  ice  in  deep 
waters,  where  the  deposit  of  river  or  ocean  sediment 
is  forming  very  slowly,  we  shall  have  an  irregular  ac- 
cumulation of  material,  without  the  regular  stratifica- 
tion of  river  deposits,  showing  only  what  may  result 
from  the  more  rapid  descent  of  the  largest  pieces, 
which,  if  they  fell  on  a  surface  already  smoothed  by 
the  more  slowly  descending  finer  sediment,  would  pre- 
sent faint  traces  of  sedimentation,  but  the  lines  would 
not  be  traceable  for  more  than  comparatively  short 
distances,  the  successive  deposits  fading  out  laterally 
and  overlapping  each  other.  Such  also  are  the  de- 
posits of  bowlder  clay  which  have  also  been  formed  by 
the  grinding  action  of  an  ice  sheet.  There  is  nothing 
to  prevent  such  deposits  carrying  ore,  except  the  irreg- 
ularity in  their  composition  on  account  of  the  wide  area 
from  which  they  may  be  drawn,  and  the  uncertain 
distribution  of  the  valuable  metals  in  the  earlier  rocks. 

GEOLOGIC  SUCCESSION  OF  EVENTS.— *It  is  scarcely  with- 
in the  scope  of  the  present  volume  to  enter  into  a 
description  of  the  geological  succession  of  the  rocks, 
as  it  would  require  a  volume  by  itself  and  be  of  little 
practical  value  to  the  miner,  except  as  regards  coal 
and  iron,  the  character  of  which  is  largely  influenced 
by  their  geologic  age,  owing  to  the  changes  which 


68  PROSPECTING  AND   VALUING  MINES. 

have  taken  place  in  their  composition  with  the  lapse 
of  time  under  the  influence  of  heat  and  pressure. 

The  accompanying  table  gives  the  outline  scheme 
adopted  by  the  U.  8.  Geological  Survey.  The  pro- 
gression is  from  the  bottom  upward,  the  order  being 
as  shown  in  the  stratified  rocks  now  accessible,  though 
the  whole  series  does  not  appear  in  any  single  locality. 
Below  the  Archaean  is  the  granite  foundation.  "Era" 
and  "period"  relate  to  time;  "system''  and  "group/9 
to  the  rocks.  Subdivisions  of  periods  and  groups  are 
called  "epochs"  and  "formations"  (according  to  time 
and  rocks  respectively).  The  names  for  these  smaller 
divisions  vary  in  different  localities,  and  authors  differ 
in  classifying  and  naming  them,  so  that  a  more  com- 
plete presentation  here  would  only  be  confusing. 

ORDER  OF  SUCCESSION  OF  GEOLOGIC   TIME   AND  ROCK  FORMA- 
TION. 


Era  or  System,  Period  or  Group. 

Era  of  Man  ............................  Quaternary. 

I  Pliocene. 
Cenozoic  or  Tertiary  ..................  •<  Miocene. 

(  Eocene. 

(  Cretaceous. 
Mesozoic  ..............................  -<  Jurassic. 

(  Triassic. 

f  Permian. 

I  Carboniferous. 
Palaeozoic  ..............................  -{  Devonian. 

I  Silurian. 

[  Cambrian. 


[See  also  the  arrangement  proposed  by  LeConte  and  Dana,  pp.  332,  323.] 


CHAPTER  IV. 
PHYSICAL  CHARACTER  OF  MINERAL  DEPOSITS. 

MINERAL  deposits  may  be  roughly  classed  under 
three  heads :  Beds,  veins  and  masses.  These  divis- 
ions correspond  to  differences  in  form,  and,  in  part, 
to  differences  in  origin. 

BEDS. — A  large  proportion  of  the  rocks  met  with 
consists  of  substances  arranged  in  distinct  stratified 
layers.  If  any  of  these  layers  consists  of  a  useful 
mineral,  or  contains  enough  to  make  it  valuable,  it  is 
said  to  be  a  deposit  in  the  form  of  a  "bed,"  "seam,"  or 
"stratum,"  sometimes  spoken  of  as  a  "bedded  vein" 
or  "blanket  vein. "  The  most  important  of  all  bedded 
or  stratified  deposits  is  coal;  but  in  addition  there  are 
beds  of  iron  ore,  copper-bearing  shales  or  slates,  lead- 
bearing  sandstones,  silver-bearing  sandstones,  gold, 
tin  and  platinum-bearing  gravels,  as  well  as  beds  of 
rock  salt,  clays,  slates,  limestones,  gypsum,  oil  shales, 
etc.  The  characteristic  feature  of  a  bed  is  that  it  is  a 
member  of  a  series  of  stratified  rocks,  and  as  such  was 
laid  down  or  formed  after  the  rocks  on  which  it  rests, 
and  before  those  which  lie  on  its  top.  This  peculiarity 
at  once  distinguishes  a  bed  from  a  true  vein. 

Eoof  and  Floor. — The  layer  above  it  is  called  the 
"roof  "of  the  deposit  and  the  onebeiowit  the  "floor," 
when  it  remains  horizontal  or  nearly  so,  but  when 
highly  inclined  the  terms  "hanging  wall"  and  "foot- 
wall,"  applied  to  true  veins,  are  equally  applicable 
to  beds,  but  less  expressive. 

Thickness. — This  is  the  distance  from   the  roof  to 


70  PROSPECTING  AND   VALUING  MINES. 

the  floor  at  right  angles  to  the  inclination  of  the  floor, 
being  the  shortest  distance  between  the  roof  and  floor, 
and  this  may  be  very  much  less  than  the  length  of  a 
crosscut  run  through  the  deposit  on  a  horizontal  line, 
the  two  becoming  nearer  in  length  as  the  bed  ap- 
proaches more  and  more  to  the  vertical ;  in  the  latter 
case  they  would  be  equal. 

Dip  is  the  inclination  of  the  floor  from  a  hori- 
zontal plane,  and  may  be  spoken  of  either  in  degrees 
of  a  circle,  as  for  example  ten  degrees  (10°);  or  ex- 
pressed in  feet,  as  1  in  10,  1  in  20,  etc.  Other  equiva- 
lent terms  are  "slope,"  "pitch"  "underlie"  and 
"inclination."  Dip,  of  course,  is  due  to  the  disturb- 
ance of  the  deposit  by  elevation  or  depression,  causing 
tilting  or  bending,  since  its  formation  (a  horizontal 
layer  having  no  dip);  but  as  such  disturbance  has 
been  almost  universal,  nearly  all  bedded  deposits  have 
more  or  less  dip,  at  the  present  day.  Sometimes  the 
beds  may  be  nearly  horizontal,  as  in  Staffordshire, 
England  ;  or  raised  to  an  angle  of  50°  as  in  the  Cumber- 
land coal  series  in  the  Skagit  Valley,  Wash.  (pi.  2,  fig. 
10);  sometimes  they  may  be  vertical  or  even  folded 
over  as  in  pi.  4,  fig.  6,  a  structure  which  is  found  in 
the  Appalachian  mountains,  and  in  some  of  the  Franco- 
Belgian  coal  fields,  where  a  vertical  shaft  passes  six 
times  through  the  same  bed,  because  the  folding  has 
been  so  complicated. 

Strike. — The  strike  or  course  of  the  bed  is  the  di- 
rection of  a  horizontal  line  drawn  along  the  floor  of 
the  deposit,  such  as  the  bottom  of  a  tunnel  following 
the  mineral,  without  grade.  This  direction  will 
clearly  be  at  right  angles  to  the  dip  of  the  bed,  and 
will  consequently  vary  as  the  dip  varies;  so  that,  if  it 
is  desirable  to  run  a  tunnel  on  a  deposit  in  a  perfectly 
straight  line,  it  must  have  a  course  or  direction  as 
nearly  as  possible  at  right  angles  to  the  general  dip, 
instead  of  to  the  dip  at  any  particular  locality.  But 
this  is  not  always  possible. 


PHYSICAL  CHARACTER  OF  DEPOSITS.  71 

From  the  above  it  will  be  clearly  seen,  by  reference 
to  pi.  13,  figs.  10,  11,  12,  13,  that  while  in  fig.  10  the 
strike  would  be  east,  in  fig.  11  it  would  vary  from 
northeast  to  east  and  thence  to  southeast;  in  fig.  12 
it  would  be  north,  going  round  by  east  until  it  was 
south;  while  in  fig.  13  it  would  turn  to  all  points  of 
the  compass  in  succession  and  indicate  a  saucer-shaped 
basin.  From  what  has  been  previously  said  it  will  be 
obvious  that  even  when  the  bed  may  be  covered  on 
the  surface  its  position,  if  it  exists  beyond  the  point 
of  discovery,  should  be  traceable  by  the  rocks  with 
which  it  is  associated ;  but  a  search  in  this  manner 
should  be  governed  by  the  rock  which  forms  the  roof, 
as  this  must  lie  comformably  above  it,  while  it  is  pos- 
sible that  the  deposit  may  lie  on  the  upturned  edges 
of  a  great  variety  of  rocks  as  at  E,  pi.  2,  fig.  1. 

The  thickness  of  workable  beds  varies  within  very 
wide  limits  according  to  their  richness  in  some  special 
mineral  or  its  scarcity.  Some  workable  beds  of  coal 
are  only  1  ft.  thick  and  range  up  to  as  much  as  60  ft. 
or  over  in  exceptional  cases.  The  copper-bearing 
shales  of  Mansfeld  are  only  from  10  to  20  in.  thick, 
while  the  lead-bearing  sandstones  at  Mechernich  are 
no  less  than  85  ft.,  and  some  beds  of  slate,  limestone 
and  salt  greatly  exceed  these  dimensions.  But  what- 
ever the  thickness  may  be  at  any  particular  point,  it 
does  not  follow  that  this  will  be  maintained  over  the 
entire  area  of  the  deposit.  Sometimes  this  may  be  the 
case  over  a  very  extensive  area,  but  there  must  neces- 
sarily be  a  boundary  to  the  deposit  in  all  directions, 
and  toward  these  limits  it  may  dwindle  away  to  a 
feather  edge,  with  the  probability  of  the  greatest 
thickness  being  near  the  central  portions  of  the  orig- 
inal deposit  (not  necessarily  that  part  left  to  our  inspec- 
tion). Toward  these  edges,  as  in  the  case  of  coal  and 
iron  deposits,  the  bed  may  contain  many  impurities 
and  become  valueless;  or  in  the  case  of  slates  and 
limestones  a  gradual  change  may  take  place  into 


72  PROSPECTING  AND   VALUING  MINES. 

another  kind  of  rock,  such  as  clay-shales  into  sand- 
stones and  these  into  conglomerates.  PL  2,  fig.  1,  D, 
shows  a  bed  of  coal,  as  originally  laid  down,  thinning 
out  in  all  directions.  It  may  consist  of  a  uniform 
mass,  with  impure  edgings,  or  it  may  be  divided  into 
several  layers  by  thin  sheets  of  clay  or  waste  matter, 
called  "partings,"  in  which  case  it  often  happens  that 
the  character  of  the  coal  above  a  parting  is  different 
from  that  below  in  important  particulars,  and  should 
be  mined  separately.  Partings  are  not  necessarily  a 
detriment  to  a  deposit,  as  they  frequently  facilitate 
mining. 

Outcrop. — It  is  not  always  easj'  at  first  sight  to  dis- 
tinguish the  outcrop  of  a  bed  from  that  of  a  true  vein, 
but  it  will  usually  be  found  more  continuous  and  more 
uniform  in  its  composition. 

VEINS  may  be  described  as  comparatively  thin  sheets 
traversing  what  are  called  " country  rocks,"  which 
were  formed  earlier  than  the  veins  themselves;  and 
occupy  crevices  formed  by  fracture  of  the  inclosing 
rocks,  or  have  been  formed  along  the  lines  of  junction 
of  such  rocks  by  changes  in  those  adjacent,,  It  is  this 
origin  at  a  later  date  than  that  of  the  rock  formation 
which  constitutes  the  essential  difference  between  a 
vein  and  a  bed. 

Dikes. — The  above  description  includes  all  veins  of 
porphyry  or  other  intruded  rocks,  such  as  granite  or 
basalt,  as  well  as  those  containing  the  useful  or  pre- 
cious minerals.  Veins  filled  with  porphyry  or  similar 
rocks  of  whatever  kind  are  usually  called  "dikes." 

True  Veins. — The  term  "vein"  is  more  properly 
restricted  to  those  which  are  more  or  less  filled 
with  useful  minerals,  whether  in  workable  quan- 
tities or  otherwise.  Building  stone  should  be  excluded 
from  this  definition,  as  many  valuable  varieties  (besides 
those  found  in  beds)  are  the  product  of  dikes.  In 
the  United  States  the  terms  "vein,"  "lode,"  "lead" 
or  "ledge"  are  used  indiscriminately  in  different 


PHYSICAL  CHARACTER  OF  DEPOSITS.  73 

localities,  but  all  have  the  same  meaning,  while  in 
Australia  and  South  Africa  the  term  "reef"  is  often 
applied  to  mineral  veins  as  well  as  to  bedded  deposits 
like  gold-bearing  conglomerates.  For  the  purposes  of 
the  U.  S.  land  offices  the  description  of  a  lode  as  given 
by  Justice  Field  in  the  celebrated  case  of  the  Eureka 
Cons.  vs.  the  Richmond  Co.  is  accepted,  viz.:  "We 
are  of  opinion,  therefore,  that  the  term  [lode],  as  used 
iu  the  acts  of  Congress,  is  applicable  to  any  zone  or 
belt  of  mineralized  rock,lying  within  boundaries  clearly 
separating  it  from  the  neighboring  rocks."  This 
definition  evidently  covers  both  true  veins  and  all 
bedded  deposits. 

Miners  often  speak  of  coal  and  iron  veins,  but  this  is 
a  misapplication  of  the  term.  When  a  bed  lies  on  the 
upturned  edges  of  much  older  rocks,  as  in  pi.  2,  fig.  1, 
E,  it  shows  conclusively  that  before  its  deposition  long 
periods  of  time  had  elapsed,  in  which  the  lower  strata 
had  been  raised  above  the  water,  uplifted  into  new 
positions,  worn  down  to  a  new  surface  and  again  de- 
pressed below  the  water  level;  and  we  can  form  some 
comparative  idea  of  the  relative  ages  of  bedded  veins 
by  the  thickness  of  the  strata  which  have  accumulated 
above  them.  In  the  case  of  true  veins  we  can  only 
judge  of  their  age  by  knowing  that  they  must  be 
younger  than  the  rocks  in  which  they  lie,  and  the 
comparative  age  of  these  is  judged  by  the  fossil 
remains  found  in  them. 

Dip. — Like  beds,  veins  have  dip,  strike  and  walls. 
As  a  usual  thing  the  dip  of  true  veins  is  apt  to  be 
steeper  than  that  of  the  majority  of  beds,  though  such 
a  distinction  is  not  absolutely  necessary.  The  dip  is 
measured  from  a  horizontal  line  as  in  the  case  of  beds, 
and  is  expresed  in  degrees.  If  the  vein  is  vertical  the 
dip  is  90°.  In  pi.  9,  fig.  1,  the  veins  A,  B,  C,  and  D, 
have  respectively  dips  of  47°,  68°  and  86°,  while  vein 
E  is  vertical  (90°).  In  some  cases  the  dip  may  be  so 
flat  that  when  the  vein  is  exposed  by  the  wearing  away 


74  PROSPECTING  AND   VALUING  MINES. 

of  the  hanging  wall  it  may  appear  almost  like  a  bed. 
Such  cases  are  often  termed  "blanket-veins,"  but  a 
very  slight  examination  will  show,  in  most  cases,  their 
true  origin. 

Strike. — Owing  to  their  different  origin,  the  strike 
of  true  veins  is  more  likely  to  have  a  uniform  direction 
than  in  beds,  as  the  inclosing  rocks  have  not  usually 
been  subjected  to  so  much  movement  since  the  forma- 
tion of  the  fissure  as  has  been  suffered  by  the  strata 
containing  the  beds;  or,  if  movement  has  taken  place, 
the  weakness  of  the  fissure  has  directed  the  motion 
into  that  plane  and  simply  caused  a  reopening  of  the 
fissure,  and  not  infrequently  a  refilling  of  it  with  a 
different  class  of  mineral  deposits.  See  pi.  6,  fig.  6, 
where  the  thin  slabs  of  rich  gold  ore  B  occur  on  each 
side  of  a  large  central  core  of  poor  or  barren  quartz  A. 
The  conclusion  is  frequently  irresistible,  taking  into 
consideration  the  great  amount  of  motion  of  the  walls 
of  the  lode  as  shown  by  their  shattered  condition,  that 
on  a  reopening  of  the  fissure  the  contents  of  the  lode 
were  concentrated  in  the  way  shown,  to  the  im- 
poverishment of  the  main  body  of  quartz. 

Outcrop  of  Veins. — The  outcrop  of  a  vein,  sometimes 
called  "croppings,"  is  the  portion  of  the  vein  exposed 
on  the  surface.  It  does  not  follow  that  the  visible  out- 
crop corresponds  with  the  true  strike  of  the  lode. 
This  can  only  occur  when  the  vein  is  vertical,  or  out- 
crops in  a  level  plain,  when  it  would  show  a  compara- 
tively straight  line  and  the  true  course,  whatever  the 
dip  mi^ht  be.  It  is  not  often  that  such  a  case  occurs, 
On  the  contrary  we  find  the  bulk  of  mineral  veins  in 
rough  and  broken  mountain  regions,  and  in  these  cases 
the  tracing  of  the  outcrop  becomes  a  more  difficult 
matter,  especially  when  the  vein  crosses  ravines  or  val- 
leys filled  up  with  gravel  or  debris  which  hide  its 
presence.  All  veins  with  a  pronounced  dip  have  a 
crooked  or  serpentine  outcrop,  and  the  fiatter  the  dip 
the  more  sinuous  this  outcrop  will  appear.  By  refer- 


PHYSICAL  CHARACTER  OF  DEPOSITS.  75 

ence  to  pi.  9,  figs.  1,  3  and  5,  these  peculiarities  will 
be  easily  understood.  Their  great  importance  be- 
comes apparent  when  making  locations  on  a  vein  and 
in  the  legal  aspect  of  these  locations.  Fig.  1  is  a 
longitudinal  section  along  the  bed  of  a  ravine,  show- 
ing five  veins  A,  B,  C,  D,  E,  and  their  outcrops  ascend- 
ing the  hill  on  the  side  furthest  from  the  observer,  as 
from  g  to  s,  h  to  r,  k  to  p,  I  to  o,  and  m  to  n.  All  the 
veins  are  supposed  to  run  north  and  south.  It  is  evi- 
dent that  on  the  crest  of  the  ridge  the  outcrop  of  the 
vein  A,  dipping  east,  will  be  west  of  its  position  in 
the  gulch  by  the  distance  sa,  while  in  the  cases  of  the 
veins  B,  C,  D,  dipping  west,  the  outcrops  on  the  ridge 
will  be  east  of  the  position  of  the  veins  in  the  bed  of 
the  gulch  as  shown  at  A,  k  and  I  by  the  distances  br, 
cp,  and  do.  It  can  also  easily  be  seen  that  on  de- 
scending the  opposite  side  of  the  hill,  the  outcrop  of 
A  would  swing  back  again  up  the  ravine,  while  all  the 
others  would  swing  down,  producing,  if  the  outcrops 
were  continuous,  an  appearance  something  like  that 
in  figs.  3  and  5.  In  fig.  3  we  have  details  of  the  out- 
crop of  two  veins,  B,  B,  and  C,  C,  running  north  and 
south  on  the  two  sides  of  a  ridge,  and  both  dipping  to 
the  west;  and  in  fig.  5  similar  details  of  two  veins  A,  At 
and  Z>,  D,  dipping  east.  The  outcrops  in  fig.  3  are 
shown  by  the  black  lines  A,  A,  and  D,  Z),  and  in  fig.  5  by 
the  similar  lines  B,  B,  and  G,  C.  A  little  study  of  these 
figures  will  make  the  matter  clear,  without  elaborate  de- 
scription. All  the  peculiarities  of  the  outcrop  may  be 
illustrated  by  taking  a  large  smooth  potato,  and  cutting 
it  into  halves  lengthwise.  Lay  the  two  halves  flat  side 
down  on  the  table  side  by  side  and  we  have  two  minia- 
ture hills  with  a  ravine  between  them.  Now  if  a  cut  be 
made  across  both  hills  inclining  from  right  to  left  we 
shall  have  a  vein  in  miniature,  and  if  the  pieces  be 
drawn  slightly  apart  so  as  to  show  the  white  of  the 
inside  in  contrast  with  the  brown  skin,  the  pale  line 
thus  made  visible  will  indicate  the  outcrop  of  the 


76  PROSPECTING  AND   VALUING  MINES. 

vein,  and  will  be  found  similar  to  figs.  3  arid  5.  By 
making  the  first  cut  flat  and  subsequent  ones  steeper 
the  gradual  approach  of  the  outcrop  to  a  straight  line 
as  the  view  becomes  more  and  more  vertical  will  be 
quickly  apparent,  until  the  vertical  cut  will  represent 
the  vein  E  in  pi.  9,  fig.  1. 

The  outcrop  may  either  be  a  very  conspicuous 
object  standing  many  feet  above  the  surrounding  sur- 
face or  barely  visible  on  the  hillside;  it  may  be  merely 
outlined  by  a  surface  depression,  or  form  a  deep  gorge, 
according  to  the  relative  hardness  of  the  vein  matter 
and  the  country  rock,  or  the  difference  in  the  contents 
of  the  vein  at  different  points  in  its  length. 

Dikes,  which  have  a  nearly  uniform  composition 
throughout  their  length,  often  traverse  a  country  for 
miles,  standing  up  like  ruined  walls,  as  at  the  Devil's 
Slide  in  Utah,  on  the  Union  Pacific  railway,  and  at 
other  places  which  nearly  every  traveler  can  recall, 
but  such  uniformity  very  seldom  exists  in  mineral 
veins.  On  the  mother  lode  of  California  the  barren 
portions  are  largely  made  up  of  threads  and  stringers, 
while  the  valuable  portions  consist  of  immense  bodies 
of  solid  quartz,  which  have  protected  the  present  hills 
from  wear  and  tear,  while  the  ravines  have  been  cut 
out  alongside  the  lode  (pi.  7,  fig.  6)  or  through  the 
barren  portions  at  right  angles,  or  nearlj*  so,  to  the 
vein,  as  in  pi.  9,  fig.  7,  where  A, A,  represent  quartz 
bodies;  B,  the  barren  intermediate  ground  and  c,c, 
the  visible  outcrops.  This  structure  is  continuous  for 
many  miles.  In  Mariposa  county  especially  the  heavy 
white  quartz  crops  out  from  the  crests  of  one  hill 
after  another,  crossing  their  summits  like  the  comb  of 
a  helmet,  in  a  most  conspicuous  manner,  with  deep 
intermediate  ravines.  In  these  cases  the  ravines  are 
due  to  the  absence  of  ore  in  the  outcrop,  but  in  other 
cases  the  ravines  are  due  to  the  presence  of  soft,  friable, 
easily  decomposed  ore  in  the  lodes,  and  form  along  the 
veins,  in  gorges  of  varying  depth  according  to  the 


PHYSICAL  CHARACTER  OF  DEPOSITS.  77 

degree  of  difference  in  hardness  between  the  lode  and 
its  wall  rocks.  A  good  illustration  of  this  structure  is 
found  in  the  Monte  Cristo  district  on  the  west  slope 
of  the  Cascade  range  in  Washington,  where  the  abrupt 
bluffs,  forming  the  walls  of  an  ancient  glacier  basin, 
are  furrowed  with  deep,  abrupt  gorges,  similar  to  pi. 
9,  fig.  6.  The  veins  here  cut  across  the  slates  with  a 
dip  of  about  60°,  and  having  undergone  extensive 
alteration,  besides  being  mineralized  with  friable  ores, 
are  now  softer  than  the  metamorphic  slates,  so  that  as 
the  vein  wore  away  the  overhanging  wedge  of  rock  B, 
broke  off  from  time  to  time,  leaving  a  steep  slope  to 
the  footwall  side  of  the  ravine,  and  a  nearly  vertical 
bluff  above  the  hanging  wall,  from  which  large  frag- 
ments are  annually  detached  by  the  action  of  frost  and 
sunshine,  widening  the  ravine,  while  at  the  same  time 
the  melting  snows  deepen  its  bed  along  the  course  of 
the  vein.  In  such  cases  the  foot  of  the  bluffs  is  cov- 
ered with  an  immense  " talus"  or  broken  rock  slope, 
consisting  of  angular  frost-detached  fragments  broken 
from  the  cliff  above,  which  have  buried  the  outcrops 
in  the  lower  portions  of  the  valley,  roughly  indicating 
their  position,  however,  by  winrows  of  immense  bowl- 
ders which  have  been  detached,  for  want  of  support, 
from  the  overhanging  wedge  B}  and  have  rolled  down 
the  slope  without  being  more  than  partially  broken 
up  in  the  fall. 

In  other  cases  the  hardness  of  the  vein  matter  and 
that  of  the  inclosing  rock  may  be  so  nicely  balanced 
that  they  both  wear  down  at  about  the  same  rate,  and 
the  croppings  may  be  covered  with  earth,  etc.,  or  as 
the  prospector  says,  "blind;"  that  is,  hidden  or  hardly 
visible;  or  the  vein  may  become  blind  because  since 
the  time  of  its  formation  new  strata  or  volcanic  over- 
flows have  been  laid  down  upon  the  containing  rocks, 
as  in  pi.  15,  figs.  13  and  14,  which  show  such  a  case 
in  longitudinal  and  cross  section.  In  this  case  if 
ravines  have  cut  down  through  the  "cap-rock"  the 


78  PROSPECTING  AND  VALUING  MINES. 

vein  may  be  seen  cropping  on  the  side  of  the  ravine  as 
at  A,  fig.  13,  being  lost  under  the  cap  B,  but  reap- 
pearing at  C  on  the  other  side  of  the  hill. 

This  cap  may  be  either  sedimentary  or  eruptive 
rock,  or  it  may  be  the  consolidated  snow  (nere)  of  a 
snowfield,  both  forms  being  seen  in  the  Monte  Cristo 
region;  so  that  the  importance  of  determining  accu- 
rately the  strike  and  dip  of  the  vein,  so  as  to  recognize 
it  on  both  sides  of  the  mountain,  becomes  very  appar- 
ent. 

But  in  whatever  manner  the  outcrops  may  occur  the 
same  rule  will  generally  hold  good  for  quite  an  exten- 
sive district  or  group  of  veins,  and  a  recognition  of 
this  fact  may  save  the  prospector  many  a  weary  mile 
of  travel  and  hard  climbing. 

If  the  vein  has  a  very  flat  dip  and  is  located  on  a 
more  or  less  conical  hill,  it  may  even  crop  entirely 
round  the  summit  of  such  a  peak,  as  shown  in  pi.  7, 
figs.  10,  11,  in  which  fig.  10  is  a  vertical  section  and 
fig.  11  a  ground  plan  of  the  same.  We  have  here  a 
series  of  trap  dikes  with  bedded  quartz  veins  lying 
between  granite  and  slate.  The  drawings  represent 
the  Yanderbilt  mine  near  Silver  Peak,  Nevada,  and 
show  a  similar  structure  to  that  of  the  Tyndall  mine 
in  Colorado. 

Spurs. — It  not  infrequently  happens  that  a  vein  pre- 
sents more  than  one  outcrop,  the  main  lode  presenting 
itself  at  the  surface  with  several  minor  lateral 
branches,  as  shown  in  the  cross  section  of  the  Dol- 
coath  mine,  pi.  7,  fig.  1.  These  are  generally  more 
numerous  on  the  hanging  wall  side  of  the  lode,  and 
present  in  the  greatest  numbers  when  the  dip  of  the 
vein  is  flat,  as  was  the  case  in  the  Comstock  lode,  of 
which  a  general  idea  is  presented  in  pi.  2,  fig.  2. 
These  ' 'spurs"  may  run  nearly  parallel  to  the  main 
lode,  and  standing  more  vertically  unite  with  it  in 
depth,  or  they  may  run  out  into  the  general  bedding 
of  the  rock,  as  shown  in  pi.  6,  fig.  2,  sys,s.  In  the 


PHYSICAL  CHARACTER  OF  DEPOSITS.  79 

former  case  it  is  easy  to  understand  how  the  cracks  in 
which  they  are  formed  were  made  by  the  weight  of 
the  overhanging  wedge  breaking  it  across  from  time  to 
time,  or  the  sliding  of  the  hanging  wall  on  the  foot- 
wall  pulling  it  apart,  a  cause  which  might  also  give 
rise  to  the  spurs  which  branch  out  into  the  bedding. 

Horses. — In  other  cases,  especially  in  very  large 
veins,  these  spurs  after  leaving  the  vein  may  reunite 
with  it  in  all  directions,  resulting  in  a  mass  of  barren 
rock  entirely  surrounded  by  vein  matter,  to  which  the 
term  "horse"  is  usually  applied.  These  are  fre- 
quently spoken  of  as  masses  of  rock  which  have  fallen 
into  the  fissure,  but  they  have  usually  moved  but  a 
very  slight  distance,  if  at  all,  from  their  original  posi- 
tion. 

Walls. — When  the  vein  is  vertical  the  walls  may  be 
distinguished  by  the  points  of  the  compass,  as  the 
north,  south,  east  or  west  wall,  but  when  the  vein  has 
a  slanting  dip  the  lower  wail  is  designated  as  the 
"foot  wall"  and  the  upper  as  the  "hanging  wall,"  as 
in  pi.  7,  fig.  7,  where  the  granite  forms  the  foot  wall, 
and  the  slates  the  hanging  wall  of  the  quartz  series  B. 
In  England  the  term  "cheeks"  is  sometimes  applied  to 
the  walls. 

Gouge. — Not  infrequently  there  occurs  between  the 
vein  matter  and  the  country  rock  a  seam  of  clayey 
matter  called  "gouge"  or  "selvage,"  which  may  be  of 
extreme  thinness  or  reach  a  thickness  of  as  much  as  30 
ft.,  as  in  the  Potosi  mine  on  the  Cromstock  lode. 
This  is  apparently  the  result  of  a  grinding  or  crushing 
movement  of  the  walls  of  the  vein  upon  each  other, 
under  enormous  pressure,  and  where  a  portion  of  the 
vein  has  been  mixed  with  material  from  the  walls  the 
gouge  is  often  rich  enough  in  mineral  to  go  to  the 
reduction  works.  Mine  clay  may  also  result  from 
chemical  decomposition  of  the  wall  rocks. 

SlicJcensides. — Where  the  motion  has  been  consider- 
able, and  the  walls  or  vein  are  hard  enough  to  resist 


80  PROSPECTING  AND   VALUING  MINES. 

the  grinding  action  and  reduction  to  clay,  both  the 
wall  and  the  vein  matter  become  marked  with  parallel 
lines  or  strice,  called  "slickensides, "  or  "slickens," 
which  indicate  the  direction  of  the  motion,  and  fre- 
quently the  quartz  or  wall  has  taken  a  polish  equal  to 
anything  which  can  be  produced  artificially. 

"Frozen"  Veins. — In  other  cases  it  may  happen 
that  there  is  only  one  well  defined  wall,  the  vein  mat- 
ter being  firmly  attached  to  the  other,  and  gradually 
fading  out  into  the  barren  country  rock,  as  shown  in 
pi.  6,  fig.  3,  where  (7,  6y,  may  be  slates  or  any  other 
rock;  A,  a  dike  cutting  the  same,  and  B  the  ore  vein 
with  a  well  defined  wall  on  the  right  hand  but 
"frozen"  to  the  dike  on  the  left  side.  The  condition 
of  the  walls  is  a  matter  of  much  interest  to  the  miner. 
If  the  ore  is  frozen  to  its  alls  on  both  sides  it  is 
almost  a  positive  indication  of  uncertainty  of  continu- 
ance in  depth,  but  heavy  clay  seams  or  gouges  are 
taken  as  favorable  indications  from  the  evidence  they 
supply  of  a  deep-seated  fissure. 

Vein  Matter. — The  material  with  which  the  vein  is 
filled  is  known  as  the  "gangue"  or  "matrix,"  usually 
by  the  former  term.  It  is  not  necessarily  quartz.  It 
may  be  limespar  (calcite,  calcspar)  fluorspar,  barytes, 
or  even  the  decomposed  remains  of  a  porphj^ry  dike. 
The  term  matrix  alludes  to  the  filling  being  the 
mother  of  the  ore.  It  does  not  follow  that  all  this 
gangue  carries  ore,  or  that  it  is  of  uniform  thickness 
through  the  entire  length  of  the  lode.  The  movement 
of  the  walls  may  have  brought  two  swells  opposite 
each  other,  as  in  pi.  6,  fig.  2,  at  B  and  in  pi.  2,  fig.  9, 
and  the  vein  is  then  said  to  "pinch"  or  "peter  out;" 
or  the  ore  maj7  be  confined  to  slabs  on  the  walls,  as  in 
pi.  6,  fig.  6,  where  B  may  represent  ore  and  A  the 
barren  quartz  gangue.  Eig.  5,  on  the  same  plate,  is 
an  exaggerated  representation  of  a  condition  fre- 
quently seen  in  the  softer  kinds  of  granite,  where 
instead  of  the  vein  pinching  completely,  as  in  fig.  2, 


PHYSICAL  CHARACTER  OF  DEPOSITS.          81 

the  motion  since  the  vein  was  filled  with  quartz  (black) 
has  been  able  to  reduce  the  portions  of  the  wall  rock 
between  the  swells  B,  B,  to  a  condition  of  gouge  or 
nearly  so,  and  a  new  wall  has  been  established  as 
WyW. 

Ore  Chutes. — It  may  happen  that  all  the  gangue  or 
matrix  is  charged  with  ore,  but  this  is  seldom  the 
case.  In  the  majority  of  cases  there  are  wide  and  long 
barren  spaces  in  the  lode  and  the  ore  is  concentrated 
into  "chutes"  (also  spelled  "shoots"),  as  shown  in 
pi.  9,  tig.  7,  A,  A.  These  may  vary  greatly  in  dimen- 
sions, being  sometimes  so  short  horizontally  in  pro- 
portion to  their  length  that  they  are  called  "pipes." 
In  addition  to  the  dip,  which  they  have  in  common 
with  the  vein,  they  have  an  inclination  to  the  right  or 
loft  of  a  line  drawn  on  the  dip  at  right  angles  to  the 
strike,  which  his  called  the  "rake."  For  instance, 
looking  down  an  incline  on  the  vein,  the  ore  may  go 
off  to  the  right  or  left  of  this  incline,  and  this  feature 
is  usually  common  to  all  the  veins  in  a  district  which 
have  the  same  strike  and  dip,  and  the  rake  is  usually 
the  greatest  in  the  flattest  veins.  In  pi.  9,  fig.  2  (a 
cross  section)  shows  the  dip  of  the  vein,  and  fig.  4  (a 
longitudinal  section)  the  rako  of  the  ore  chute  C, 
which  is  estimated  from  the  true  dip  line,  in  this  case 
37°. 

MASSES. — Under  this  head  are  included  irregular 
deposits  which  cannot  be  classed  as  either  beds  or 
veins.  Their  forms  are  various,  and  sometimes  they 
are  mereb'  indefinite  impregnations  in  permeable 
ground,  leached  out  from  finely  disseminated  mineral 
in  the  surrounding  country  rocks.  Some  iron  and 
manganese  ore  bodies,  formed  in  troughs  or  cup- 
shaped  depressions,  are  best  described  as  "masses,"  as 
also  are  many  segregated  deposits  of  tin,  copper,  and 
silver  ores.  The  most  pronounced  type  is  perhaps  to 
be  found  in  the  large  isolated  bodies  of  lead  and  zinc 
ores  in  limestone.  Small  deposits,  of  whatever  min- 


82  R08PECTING  AND   VALUING  MINES. 

eral,  are  called  "pockets"  or  "bunches."  The  main 
characteristics  of  masses  are  irregularity  and  isolation  ; 
but  these  do  not  prevent  their  being,  in  many  instances, 
very  valuable.  If  their  shape  is  decided  in  any  direc- 
tion, they  may  be  said  to  have  strike,  dip,  rake  or 
pitch,  roof  and  floor,  or  walls,  etc. 


CHAPTER  Vo 
ORIGIN  OF  VEINS. 

ALL  veins  of  whatever  kind,  whether  bearing  valua- 
ble minerals  or  not,  are  the  result  of  movements  in  the 
upper  portions  of  the  earth's  crust,  producing  cracks 
or  crevices,  which  have  been  subsequently  enlarged 
and  filled  with  some  material  different  in  its  physical 
and  chemical  qualities  and  appearance  from  the  rocks 
in  which  the  fracture  has  taken  place. 

These  movements,  which  may  be  the  result  of  earth- 
quakes, or  the  readjustment  of  the  pressure  caused  by 
the  thinning  of  one  portion  of  the  crust  by  denuda- 
tion and  the  thickening  of  another  portion  by  the 
deposition  upon  it  of  all  the  material  brought  down 
from  the  mountains  by  the  action  of  rivers,  are  inti- 
mately connected  with  the  process  of  mountain  build- 
ing, and  consequently  show  themselves  most  striking!}* 
in  mountain  regions,  in  which  also  volcanic  agencies 
have  played  a  most  important  part. 

FISSURES  AND  FAULTS. — Such  fractures  in  the  rocks, 
when  they  have  been  accompanied  with  more  or  less 
motion  of  one  side  of  the  mass  upon  the  other,  or  of 
both  on  each  other,  are  known  as  "faults'*  or  disloca- 
tions. They  may  show  themselves  only  by  a  mass  of 
broken  material,  or  the  break  may  be  comparatively 
clean-  cut,  and  may  be  very  short,  or  extend  for  many 
miles,  as  in  New  Zealand,  where  one  earthquake  (1845) 
produced  a  fissure  in  the  southern  island  which  aver- 
aged 18  in.  in  width  and  was  traceable  for  a  distance 


84  PROSPECTING  AND  VALUING  MINES. 

of  60  miles  parallel  to  the  axes  of  the  mountain  chain, 
while  the  earthquake  of  1855  gave  rise  to  a  fracture 
which  could  be  traced  along  the  base  of  a  line  of  cliffs 
for  a  distance  of  about  90  miles. 

But  whatever  the  cause  and  however  long  the  fissure 
may  be,  it  must  terminate  at  each  end  somewhere, 
otherwise  it  would  cut  the  world  in  two;  and  it  is  evi- 
dent that  however  great  the  elevation  or  depression  of 
the  bounding  walls  at  any  one  point,  there  can  be  no 
such  motion  at  its  two  extremities;  and  that  the 
grinding  action  of  the  motion,  which  prepares  the  fis- 
sure for  the  formation  of  a  mineral  vein,  must  be 
nothing  at  either  end,  and  greatest  where  the  displace- 
ment of  the  walls  has  been  most  extensive. 

It  does  not,  however,  follow  that  all  fissures  will 
produce  mineral  veins,  for  there  must  be  a  combina- 
tion of  circumstances  to  cause  such  depositions;  but 
as  these  faults  may  have  been,  and  often  have  been, 
formed  subsequent  to  the  formation  of  bedded  de- 
posits such  as  those  of  coal,  iron  or  gold-bearing 
gravels,  it  is  therefore  necessary  to  know  something 
of  the  features  which  these  faults  present  to  enable  us 
to  again  find  a  broken  bed  or  vein  when  lost  in  the 
course  of  working. 

Throw. — The  simplest  form  of  fissure  is  shown  on 
pi.  3,  fig.  4,  AB,  with  the  greatest  motion  at  n,o;  CD 
in  the  same  figure  (after  Geikie)  shows  a  fissure  split- 
ting at  the  ends  into  minor  branches,  the  amount  of 
"throw"  or  displacement  of  the  walls  being  given  in 
figures,  which  indicate  the  greatest  movement  in  the 
middle,  as  before  explained ;  while  EF  shows  one  in 
which  the  walls  have  been  drawn  apart  at  right  angles, 
or  nearly  so,  to  the  main  fissure,  forming  "spurs."  A 
similar  structure  is  shown  in  pi.  6,  fig.  2.  In(7Z>,  pi. 
3,  fig.  4,  while  the  greatest  total  movement  has  been 
say  30  ft.  it  does  not  follow  that  all  this  movement  was 
on  one  side  of  the  fissure,  for  one  side  may  have  been 
raised  and  the  other  depressed  in  varying  proportions. 


ORIGIN  OF  VEINS.  85 

These  figures  are  horizontal  plans.  PL  1,  figs.  3,  4,  5 
6,  7,  show  the  simplest  kind  of  fault  in  vertical  cross 
section,  if  the  break  were  an  absolutely  straight  line, 
which,  however,  is  not  often,  if  ever,  the  case.  Fig. 
3  shows  a  fracture  in  a  series  of  bedded  rocks  without 
any  apparent  displacement,  although  it  is  possible  that 
there  might  have  been  such  horizontally.  Figs.  4  and 
5  show  a  movement  of  either  or  both  of  the  two  walls 
on  each  other  in  the  direction  of  the  arrowheads;  but 
there  would  be  nothing  in  such  a  case,  as  the  fracture 
is  clean  cut,  to  indicate  the  dij'ection  in  which  the 
movement  had  taken  place,  whether  the  foot  wall  had 
been  depressed  as  in  fig.  5  or  elevated  as  in  fig.  4,  or 
the  reverse  in  the  case  of  the  hanging  walls;  but  in 
fig.  6,  7,  the  movement  is  clearly  shown  by  the  bent 
and  broken  edges  of  the  strata,  to  be  an  ordinary  fault 
or  depression  of  the  hanging  wall  in  fig.  6. 

Reverse  Throw. — Elevation  of  the  hanging  wall  (or 
depression  of  the  foot  wall)  is  shown  in  pi.  1,  fig.  7. 
Such  a  throw  is  also  seen  in  pi.  11,  fig.  5,  from  the 
gravel  pit  at  Laporte,  Cal.  The  direction  of  the 
throw  is  called  the  "hade. " 

Pockets  Formed  by  Faulting. — If  a  fault,  instead 
of  being  a  clean,  straight  cut,  has  a  sinuous  or  wavy 
form,  as  in  pi.  2,  fig.  7,  the  result  of  motion  of  the 
walls  in  the  direction  of  the  arrowheads  would  be  very 
different,  producing  the  form  shown  in  fig.  8,  or  a 
vein  of  very  uniform  width  throughout,  if  the  move- 
ment were  a  mere  separation  horizontally;  whereas,  if 
the  movement  had  been  in  the  direction  of  the  arrows 
in  fig.  9,  the  swells  of  one  wall  may  have  been  brought 
against  the  swells  of  the  other  wall,  resulting  in  a 
series  of  lens-shaped  pockets,  especially  if  the  course 
or  strike  of  the  lode  be  also  sinuous  and  it  has  suffered 
more  or  less  longitudinal  as  well  as  vertical  displace- 
ment. On  sinking  on  the  outcrop  at  a,  fig.  9,  the  vein 
would  be  found  widening  rapidly,  forming  what  the 
Mexicans  call  an  "A"  vein;  while,  if  the  surface  had 


86  PROSPECTING  AND  VALUING  MINES. 

been  worn  away  to  the  dotted  line  be,  similar  sinking 
would  reveal  a  vein  rapidly  diminishing  in  width  or  a 
"V"  vein. 

Very  rapid  widening  of  an  ore  body  in  this  way  is 
liable  to  be  accompanied  by  an  equally  rapid  contrac- 
tion, and  vice  versa.  An  easy  method  of  getting  a 
thorough  understanding  of  this  important  phase  of 
fissure  structure  is  to  tear  a  piece  of  paper  in  two 
halves  along  a  wavy  line  such  as  is  shown  on  pi.  2,  fig. 
7;  when,  by  moving  them  apart  in  various  directions 
upon  a  dark  background,  every  phase  of  the  question 
can  be  readily  studied,  particularly  if  in  one  instance 
the  waves  are  made  short  and  deep,  and  in  another 
long  and  gentle.  PL  6,  fig.  5,  is  an  exaggerated  illus- 
tration of  such  structure,  to  show  that  when  the  ore 
(black)  is  lost  at  B  the  search  for  the  next  swell  must 
be  continued  by  following  the  crosshead  or  seam  which 
cuts  the  ore  body  off  (this  being  the  original  fissure 
line),  and  not  by  following  the  false  wall  W  W,  which 
has  only  been  formed  by  the  motion  and  pressure 
crushing  the  swells  of  the  country  rock  AB  into  a  shat- 
tered mass  of  vein  matter;  or,  yet  worse,  by  presum- 
ing that  the  course  of  the  ore  body  is  the  general 
course  of  the  vein,  and  following  that  direction  into 
the  country  rock  on  one  of  the  joints  which  originally 
determined  the  shape  and  position  of  the  swells  on  the 
line  of  fracture. 

Gashes. — When  such  fissures  have  been  formed  by 
pressure  from  below  bulging  the  surface  upward  as  in 
pi.  2,  fig.  4,  a  simple  gash  may  have  been  formed, 
which  was  later  on  filled  with  mineral  matter  from 
above  or  laterally;  or  by  the  action  of  surface  waters, 
became,  as  we  so  often  find,  the  line  of  a  watercourse 
following  an  anticline  e.  A  sagging  in  a  syncline 
might  conceivably  give  rise  to  the  opposite  effect,  as 
in  fig.  5. 

Step  Faults. — In  other  cases,  the  elevation  has  been 
so  great,  and  the  strain  on  the  strata  so  enormous  that 


ORIGIN  OF  VEINS.  87 

when  they  did  give  way  the  central  mass  with  the 
largest  base  exposed  to  the  elevating  force  has  been 
thrust  furthest  upward,  while  the  masses  on  either 
side  have  settled  down  in  gradually  lessening  steps 
until  the  movement  fades  out  into  undisturbed  coun- 
try, producing  a  series  of  "step  faults/'  of  which  pi. 

1,  fig.  1  is  an  ideal   and  fig.  2  an  actual  illustration, 
the  latter  being  taken  from  the  reports  of  Prof.  Em- 
mons  on  Leadville,  Col.,  where  the  drop  of  2,000  ft. 
at  the  Mosquito  fault  is  reduced   going  westward   to 
only  750  ft.  at  the  Carbonate. 

Trough  Faults. — The  faults  shown  in  pi.    3,  figs.    1, 

2,  3,  known    as  " trough    faults/'   are  more   compli- 
cated, and  are  best  explained  in  the  language  of  Mr. 
Jukes,  who  proposed  the  following   satisfactory  solu- 
tion   of   the    problem:     "Suppose  the  beds  AA,  BB, 
etc.,  fig.  2,  to  have  been  formerly  in  a  state  of  tension, 
arising  from  the  bulging  tendency  of  an  internal  force, 
and  one  fissure,  FE,  to  have  been  formed  below,  which 
on  its  course   to  the  surface  splits  into  two,  ED  and 
EC.     If  the  elevatory  force  were  then  continued,  the 
wedge-like  piece  of  rock   between   these  two  fissures, 
being  unsupported,  as  the  rocks  on   each   side  sepa- 
rated, would  settle  down  into  the   gap  as  in  fig.  3.     If 
the  elevatory  force  were  greater  near  the  fissure  than 
further  from  it,  the  single  fissure  below  would  have  a 
tendency    to    gape    upward,    and    swallow    down  the 
wedge,  so  that  eventually  this  might  settle  down,  and 
become  fixed  at  a  point  much  below  its  previous  rela- 
tive position.     Considerable  friction  and  destruction 
of  the  rocks,  so  as  to  cut  off  the  corners  g,  h,  fig.  3,  on 
either  side,  would  probably  take  place  along  the  sides 
of  the  fissures,  and  thus  widen  the  gap,  and  allow  the 
wedge-shaped    piece    to    settle    down    still    further. 
When   the   forces    of   elevation    were   withdrawn,  the 
rocks  would  doubtless  have  a  tendency  to  settle  down 
again,  but   these    newly  included    wedge-shaped    and 
other  masses  would  no  longer  fit  into  the  old  spaces, 


88  PROSPECTING  AND   VALUING  MINES. 

so  that  great  compression  and  great  lateral  pressure 
might  then  take  place/'  PI.  4,  fig.  5,  (after  Jukes) 
shows  such  a  fault  or  wedge  cutting  into  a  bed 
of  coal,  which  from  the  enormous  pressure  resulting 
from  the  resettlement  of  the  strata  "has  been  reduced 
to  a  paste  of  coal  dust  and  very  small  coal." 

Very  frequently  the  line  of  fault  becomes  the  bed  of 
a  watercourse  and  in  time  a  ravine.  This  may  result 
not  only  from  the  weaker  nature  of  the  rock  on  this 
line  (as  evidenced  by  the  faulting  itself),  but  also 
from  the  tilting  of  strata  along  the  fault  plane.  Such 
a  fault-formed  valley  may  or  may  not  at  present  be 
occupied  by  a  watercourse.  PL  12,  fig.  9,  shows  a 
canon  following  a  fault  in  Death  Valley,  Cal. 

Every  mountain  region  is  full  of  faults,  and  they 
abound  especially  along  the  great  ranges,  where  the 
movements  have  been  so  great  as  to  bring  to  the  sur- 
face, alongside  of  each  other,  rocks  which  in  the  order 
of  succession  are  separated  by  many  thousands  of  feet; 
and  in  these  movements  we  have  an  explanation  of  the 
sudden  change  in  the  character  of  mineral  deposits  on 
opposite  sides  of  lofty  mountain  chains  which  some- 
times seem  inexplicable.  But  almost  every  vertical 
exposure  of  rock  in  such  places  as  railroad  cuttings, 
and  not  only  of  rock  but  of  unsolidified  beds  of  sand 
or  gravel  and  clay,  shows  a  multitude  of  minor  fis- 
sures intersecting  and  displacing  each  other,  some- 
times in  the  most  complicated  manner,  but  presenting 
evidence  of  the  universality  of  the  process  which  has 
opened  the  way  for  the  circulation  of  underground 
waters,  without  which  it  would  seem  that  the  filling  of 
a  portion  of  the  fissures  could  not  have  been  accom- 
plished. 

There  does  not  appear  to  have  been  any  time  in  the 
earth's  history  since  the  first  solidifying  of  the  surface 
when  such  fracturing  and  movements  have  not  been 
going  on,  and  consequently  we  find  veins  of  one  age 
intersected  and  sometimes  dislocated  by  others  formed 


ORIGIN  OF  VEINS.  89 

on  fractures  of  later  date,  until  in  some  cases  there 
may  result  a  very  complicated  condition,  as  shown  in 
pi.  2,  fig.  6,  which  a  thorough  knowledge  of  the 
theories  of  faulting  alone  can  explain,  and  for  want  of 
which  loss  and  disappointment  may  ensue  from  min- 
ing operations  therein.  It  does  not,  however,  follow 
that  because  one  vein  may  be  apparently  faulted  and 
thrown  by  another,  such  is  always  the  case,  as  at  the 
crossing  of  AA  and  (7(7,  where  the  fissure  A  may 
have  jumped  along  0  because  the  line  of  least  resist- 
ance may  have  been  different  on  the  two  sides  of  (7, 
which  would  make  A  younger  than  O\  but  where  the 
dragging  of  the  rocks  is  present,  as  at  the  intersection 
of  AA  with  BB,  the  presumption  is  strong  in  the 
absence  of  other  evidence  that  AA  has  been  faulted 
and  thrown  by  BB. 

Clockworks. — The  complication  arising  from  these 
sources  may  be  so  intricate  that  it  becomes  impossible 
to  say  which  set  of  fissures  is  of  most  ancient  date, 
and  they  may  become  so  numerous  and  minute  that 
individual  mining  becomes  an  impossibility,  and  the 
mass  is  extracted  as  a  whole,  if  extracted  at  all,  under 
the  name  of  a  "stock work. " 

Rocks  vary  so  greatly  in  their  hardness,  texture, 
composition,  brittleuess,  and  facility  of  splitting  that 
they  break  in  very  different  ways,  and  this  peculiarity 
must  inevitably  exert  an  influence  on  the  character  of 
the  fissures  by  which  they  may  be  traversed,  and  a 
knowledge  of  what  may  be  expected  in.  each  case  is 
essential  to  a  clear  understanding  of  the  methods  to 
be  employed  in  opening  and  working  mineral  veins  to 
the  best  advantage. 

" True  Fissure  Veins." — Anyone  of  the  faults  shown 
in  pi.  1,  which  must  evidently  extend  downward  to  an 
unknown  depth,  may  under  certain  conditions  form 
what  is  known  as  a  "true  fissure  vein"  (an  old-time 
term  for  what  was  thought  to  be  the  best  and  most 
permanent  type  of  a  mineral  deposit),  which  is  simply 


00  PROSPECTING  AND  VALUING  MINES. 

a  fissure,  sometimes  miles  in  length,  coursing  directly 
across  the  country  in  a  more  or  less  straight  line,  and 
cutting  through  the  rocks  indiscriminately,  but  vary- 
ing in  width  and  character  according  to  the  rock  in 
which  it  may  occur  both  in  length  and  depth,  and 
tilled  with  mineral  matter  other  than  eruptive  rocks. 

Strike  Faults. — A  fault  may  cut  the  rock  formations 
at  right  angles  to  their  strike,  or  it  may  run  more  or 
less  parallel  with  the  strike,  but  cut  the  rocks  on  their 
dip,  by  being  usually  more  nearly  vertical  than  the 
strata  penetrated,  in  which  case  the  vein  would  be 
formed  on  a  "strike  fault/'  and  at  the  surface  present 
many  resemblances  to  what  is  known  as  a  "contact 
vein." 

Effect  of  Country  Bocks  on  Fissures. — If  the  fissure 
is  entirely  in  the  same  rock  it  may  maintain  a  toler- 
ably uniform  character  for  its  entire  length  and  depth, 
but  if  it  cut  rocks  of  various  kinds  it  may  pinch  out 
almost  entirely  in  those  which  are  tough,  expanding 
in  those  which  fracture  more  easily,  either  from  split- 
ting readily  (as  slates)  or  from  extra  brittleness  (as 
certain  quartzites).  If  it  traverse  a  limestone  forma- 
tion it  may  for  a  time  completely  Jose  the  character  of 
a  fissure  vein  with  definite  walls,  in  a  comparatively 
short  time  after  its  formation,  on  account  of  the  great 
facility  with  which  lime  is  removed  by  the  action  of 
water,  especially  when  containing  carbonic  acid,  and 
the  irregular  cavernous  structure  thus  caused. 

It  therefore  becomes  an  important  question  when 
ore  is  found  in  a  certain  rock  to  ascertain  to  what 
extent  that  rock  is  developed,  and  whether  the  associ- 
ated rocks  are  of  such  a  character  for  hardness  or  soft- 
ness that  a  vein,  as  the  miners  say,  can  live  in  it* 
The  writer  has  in  mind  an  extensive  region  where  the 
disregard  of  these  general  principles  has  led  to  the 
useless  expenditure  of  large  sums  on  veins  which  a 
very  slight  geological  knowledge  would  have  taught 
the  miners  could  not  be  of  permanent  value,  because, 


ORIGIN  OF  VEINS.  91 

however  rich  the  surface  ores,  they  were  contained  in 
the  fragments  of  a  bed  of  schists  overlying  a  tough 
solid  syenite,  in  which  the  vein  exposures  were  very 
narrow,  and  into  which  the  veins  found  in  the  schists 
would  inevitably  pass  in  their  lower  portions. 

If  the  vein  has  been  formed  on  a  strike  fault,  there 
is  a  yet  greater  chance  of  irregularity  from  the  ten- 
dency of  the  break  at  times  to  follow  the  bedding 
planes  of  the  rocks,  while  at  others  it  cuts  through 
them,  resulting  in  shattered  masses  which  form 
"horses"  or  barren  patches  of  country  rock  in  the 
middle  of  the  ore  body  ;  or  the  fracturing  may  have 
been  so  extensive  laterally  that  we  have  a  mass  of 
parallel  threads  and  stringers,  instead  of  a  smaller  but 
more  compact  deposit. 

CONTACT  VEINS. — From  such  veins  as  the  latter  the 
passage  is  easy  to  those  formed  on  the  contact  of  two 
bodies  of  rock  of  different  kinds.  Such  contacts  may 
be  divided  into  four  groups:  (1)  Contacts  between 
sedimentary  rocks  such  as  slate  and  quartzite,  quart- 
zite  and  limestone,  or  sandstone  and  conglomerate; 
(2)  contacts  between  sedimentary  and  intrusive  or 
igneous  rocks,  such  as  slate  and  granite,  or  limestone 
and  porphyry;  (3)  contacts  between  two  igneous 
rocks  as  porphyry  and  syenite;  and  (4)  contacts  on 
the  walls  of  dikes  which  may  traverse  a  series  of  either 
sedimentary  or  igneous  rocks. 

When  contact  veins  of  the  first  two  classes  stand  at 
a  high  angle  or  approach  the  vertical  there  is  at  first 
sight  but  little  difference  in  their  appearance  from 
fissure  veins,  but  as  they  alwa37s  maintain  the  same 
relation  to  the  inclosing  rocks  they  are  apt  to  have  a 
more  uniform  character  both  in  structure  and  filling. 
It  is  plain  also  that  they  must  partake  of  all  the  wavy 
irregularities  of  shape  which  have  been  imparted  to 
the  rocks  in  their  upheaval,  and  if  followed  downward 
to  a  sufficient  depth  must  eventually  flatten  out,  as  no 
beds  of  stratified  rock  can  continue  to  descend  toward 


92  PROSPECTING  AND  VALUING  MINES. 

the  center  of  the  earth  indefinitely,  from  the  very 
nature  of  their  origin;  still,  the  contact  is  usually  of 
great  extent,  and  there  is  no  reason  why  the  vein 
should  not  be  so  also. 

This  feature  becomes  especially  pronounced  when 
the  contact  lies  nearly  horizontal  or  only  slightly 
inclined,  as  at  Leadville,  because  we  are  able  to  reach 
it  with  comparatively  shallow  shafts  over  large  areas, 
the  extent  of  w7hich  in  one  direction  represents  the 
strike  of  a  vertical  lode,  while  the  extent  in  the  other 
is  practically  the  same  as  the  depth  reached  on  the 
vertical  lode  only  by  deep  sinking  with  all  its  limita- 
tions. In  such  horizontal  contact  deposits  we  do  not 
look  for  horizontal  motion,  and  have  only  to  encounter 
the  troubles  arising  from  subsequent  faulting,  as  in  pi. 
1,  figs.  1  and  2,  but  in  many  cases  of  steeper  contacts 
there  are  evidences  of  vertical  motion,  in  which  case 
we  shall  usually  find  the  contact  to  be  local  and  acci- 
dental ;  the  fissure  being  really  a  strike  fault  con- 
tinued to  the  surface  on  a  contact  plane  which  proved 
to  be  the  line  of  greatest  weakness,  as  in  the  case  of 
the  Comstock  lode  in  Nevada,  which  strikes  nearly 
parallel  with  the  axis  of  the  mountains  on  whose  flanks 
it  is  located,  and  presents  varying  contacts  in  Virginia 
City,  Gold  Hill,  and  Silver  City,  but  has  been  proved 
to  descend  into  the  syenite  at  Virginia  City,  below 
the  level  of  the  Sutro  tunnel,  the  character  of  the  lode 
changing  at  the  same  time  as  well  as  the  composition 
of  the  ore.  Thus  evidence  of  motion  in  an  apparently 
contact  vein  may  be  taken  as  prima  facie  proof  that 
the  contact  is  not  continuous,  and  that  the  vein  really 
belongs  to  the  group  of  fissure  veins,  and  will  partake 
of  all  their  peculiarities  of  structure  and  filling. 

When  two  sedimentary  rocks  are  conformable,  but 
have  a  more  or  less  wavy  surface  of  junction,  a  sliding 
movement  of  one  upon  the  other  will  give  rise  to  open- 
ings and  pinches,  just  as  in  the  case  of  secondary 
faults  on  warped  planes  in  homogeneous  rock,  and  an 


ORIGIN  OF  VEINS.  93 

opportunity  for  the  formation  of  a  contact  vein  is 
presented,  as  in  pi.  1,  fig.  8.  Such  a  vein  might  be 
regarded  as  either  a  contact  deposit  or  a  fissure  vein, 
but  is  more  naturally  considered  in  the  former  class. 

As  the  rocks  on  the  two  sides  of  a  contact  are  seldom 
of  equal  hardness  the  character  of  the  vein  will  prob- 
abbr  be  governed  by  that  which  is  most  liable  to 
decay,  removal  or  fracturing.  This  is  especially  the 
case  with  slates  and  limestones,  the  former  on  account 
of  the  facility  with  which  they  split  and  crush;  the 
latter  because  they  are  so  easily  dissolved. 

Compression  Veins. — No  person  with  any  experi- 
ence in  the  mountains  can  have  failed  to  notice  the 
folds  and  bends  in  slate  rocks,  from  gentle  waves  to 
minute  crumplings,  which  have  been  produced  by 
forces  pressing  on  the  ends  of  the  lines  of  stratifica- 
tion, until  a  structure  similar  to  that  shown  in  pi.  6, 
fig.  1,  has  been  reached,  a  structure  which  can  be 
easily  imitated  by  squeezing  the  leaves  of  a  book  to- 
gether endwise,  between  the  covers,  held  slightly 
apart.  If  such  slates  are  on  a  line  of  contact,  as  at 
the  Keystone  mine,  Amador  County,  Cal.,  and  have 
been  subjected  to  such  pressure,  many  good  mines 
have  been  the  result;  but  where  such  action  has  taken 
place  in  the  body  of  a  large  mass  of  slate,  in  the 
absence  of  an3r  special  controlling  element,  such  as  a 
dike,  great  uncertainty  will  exist  as  to  the  extent  of 
the  movement,  which,  having  full  play  in  all  direc- 
tions, may  have  simply  resulted  in  a  multitude  of 
irregular  minor  foldings.  In  all  such  cases  the  whole 
vein  does  not  consist  of  a  continuous  sheet  of  ore, 
although  there  may  be  such  at  the  immediate  contact, 
but  of  a  series  of  lenticular  masses,  overlapping  each 
other,  which  may  occupy  a  belt  several  hundred  feet 
in  width,  the  broadest  portion  of  one  being  generally 
opposite  the  thin  end  of  another.  It  is  obvious  that 
such  mines  will  require  extensive  cross-cutting  to 
make  certain  that  no  ore  body  has  been  overlooked. 


94  PROSPECTING  AND  VALUING  MINES. 

Limestone  Contacts. — In  a  limestone  contact, 
whether  steep  or  flat,  the  actual  line  of  contact  which 
will  form  one  wall  of  the  lode  may  be  comparatively 
smooth,  while  that  in  the  limestone  may  be  very 
irregular,  depending  somewhat  on  the  solidity  of  the 
limestones  or  their  varying  degrees  of  solubility,  and 
the  destruction  of  the  limestone  by  this  means  may  be 
so  complete  that  the  ore  body  will  apparently  consist 
of  a  cemented  conglomerate,  the  pebbles  in  which  are 
only  the  insoluble  cherty  or  flinty  residue  so  abundant 
in  chalk  and  silicious  limestones. 

The  remaining  groups  may  be  considered  together, 
as  while  there  may  be  cases  of  contact  of  two  eruptive 
rocks  without  the  presence  of  a  dike,  as  on  the  Corn- 
stock,  the  majority  of  contact  veins  in  purely  eruptive 
rocks  are  alongside  of  or  controlled  by  dikes  cutting 
masses  of  some  other  variety,  as  in  many  Colorado 
mines.  The  essential  feature  of  all  lodes  formed  on 
the  contact  of  dikes  is  that  the  latter  have  been 
squeezed  from  below  into  the  fissures  as  they  were 
formed,  and  that  consequently  their  walls  must  extend 
downward  to  the  source  of  the  pasty  rock  with  which 
they  were  filled,  and  that  this  source  is,  in  depth, 
beyond  our  ability  to  explore.  While  such  contact 
lodes  thus  present  a  general  similarity  to  fissure  veins 
in  their  length  and  depth,  they  possess  one  important 
feature  not  present  in  the  latter — that  one  wall  of  the 
fissure  is  always  of  the  same  composition,  a  fact  which 
will  tend  to  maintain  a  more  uniform  character  in  the 
filling,  at  least  on  one  side  of  the  vein.  The  wall  away 
from  the  dike  will,  of  course,  be  liable  to  changes  as 
the  rock  of  which  it  is  formed  varies,  but  such  changes 
will  be  rather  those  incident  to  the  influence  of  the 
heat  of  the  injected  dike,  as  the  baking  of  clay  shales 
into  jaspery  or  flinty  products,  rather  than  variations 
in  the  shattering  of  the  walls,  as  the  forcing  apart  of 
the  walls  of  the  fissure  and  simultaneous  filling  with  a 
plastic  substance  would  prevent  grinding  of  the  faces 


ORIGIN  OF  VEINS.  95 

of  the  fissure  against  each  other,  while  such  fragments 
of  the  walls  as  did  fall  off  would  be  buried  in  the 
intruded  mass,  and  carried  by  it  upward  on  its  course 
toward  the  surface  if  the  rent  extended  that  far.  In 
such  lodes  we  may  find  a  sudden  change  in  the  prin- 
cipal mineral  on  passage  from  one  rock  to  another,  but 
^  constant  admixture  of  some  other  ingredient  which 
owes  its  presence  to  that  of  the  adjacent  dike; 
Dr  the  ore  on  one  wall  may  be  of  a  totally  different 
character  from  that  on  the  other,  as  at  the  Key- 
stone mine,  where,  next  to  the  so-called  green- 
stone hanging  wall,  the  quartz  is  massive,  white  and 
blocky,  while  that  of  the  slate  foot  wall  is  banded  with 
numerous  parallel  blackish  lines  of  slate,  making  the 
"ribbon  rock"  of  the  miners;  or,  as  on  the  Comstock, 
where  the  nearly  vertical  ore  bodies  in  the  porphyry, 
as  they  approach  the  much  flatter  syenite  foot  wall, 
carry  an  appreciably  larger  proportion  of  gold ;  or,  as 
at  a  mine  in  northern  Washington,  the  ore  on  one  wall 
may  be  distinctly  a  silver  proposition,  and  on  the 
other,  only  15  ft.  away,  as  decidedly  a  gold  one. 

In  all  these  cases  of  dike  contacts,  the  point  at 
which  ore  will  form  and  the  shape  of  the  deposits  will 
be  governed  by  the  same  influences  as  in  other  con- 
tacts, whether  the  lode  has  been  formed  by  the  gradual 
shrinkage  of  the  mass  of  the  dike  in  cooling,  or  by 
substitution  through  the  circulation  of  water  along  its 
bounding  planes. 

Gash  Veins. — Shrinkage  of  sheets  of  lava  may  also 
produce  veins  which  will  not  extend  into  the  underly- 
ing granite  or  other  rock,  as  at  the  Stonewall  Jackson 
mine,  Ariz.  Such  occurrences  may  be  classed  with 
the  "gash  veins." 

Segregated  Veins. — In  other  cases,  like  that  shown 
in  pi.  7,  fig.  5,  there  may  be  neither  a  clean  cut  fissure 
nor  a  line  of  contact,  nor  a  controlling  dike,  but  a 
series  of  ore  bodies  arranged  along  a  general  line  of 
shattering  and  without  definite  walls,  the  change  in 


96  PROSPECTING  AND  VALUING  MINES. 

the  rock  becoming  gradually  less  marked  laterally  until 
it  fades  out  into  the  unaltered  country  rock.  Such 
occurrences  are  known  as  "segregated  veins, "  by 
which  term  it  is  understood  that  the  mineral  has  been 
concentrated  by  the  action  of  water  into  the  crevices 
of  a  shattered  or  sheeted  belt  of  rocks  from  the  sur- 
rounding rocks  themselves.  This  "sheeting"  is  well 
seen  in  many  mines  in  granite,  where  an  apparently 
solid  and  smooth  wall  will  scale  off  in  slabs  or  sheets, 
after  a  short  exposure  to  the  air,  making  it  almost  im- 
possible to  say  where  the  true  wall  may  be,  and  ren- 
dering a  large  opening  necessary  to  secure  a  relatively 
small  amount  of  ore.  Many  miners  make  the  mistake 
of  considering  all  the  sheeted  mass  as  a  part  of  the 
vein,  thus  deceiving  themselves  with  the  hope  that  the 
ore  body  may  ultimately  be  as  wide  as  the  sheeted  por- 
tion. A  little  study  will  show  the  falsity  of  such  a 
notion,  as  it  is  quite  conceivable  that  the  step  faults 
shown  in  pi.  1,  fig.  1,  might  be  so  numerous  that  the 
spaces  between  would  not  exceed  the  thickness  of  the 
slabs  just  spoken  of.  Most  faults  through  rocks  which 
do  not  break  too  easily  into  small  fragments  show  this 
sheeted  structure,  as  the  result  of  the  dragging  of  the 
sides  at  the  moment  of  fracture.  Where  there  has 
been  much  of  this  action  we  may  look  for  more  or  less 
numerous  veins  parallel  to  the  main  lode  of  a  district, 
which  maj'  carry  more  or  less  ore,  but  being  only  inci- 
dents accompanying  the  principal  disruption  are  less 
likely  to  afford  the  conditions  which  will  develop  them 
into  lodes  of  equal  value. 

GENERAL  CONCLUSIONS. — It  may  therefore  be  set  down 
as  an  axiom  in  mining  that  as  a  prior  condition  to  the 
formation  of  mineral  veins  there  must  have  been  such 
fracturing  of  the  rocks  as  to  facilitate  the  circulation 
of  underground  waters  vertically  as  well  as  horizon- 
tally, and  that  the  nature  of  the  fissures  thus  produced 
will  be  influenced  by  the  varying  hardness,  brittleness 
or  solubility  of  the  rocks  thus  fractured,  as  well  as  by 


ORIGIN  OF  VEINS.  97 

the  direction  in  which  the  force  may  have  been  applied. 
The  "filling"  of  the  vein  will  depend  on  other  condi- 
tions, but  one  may  reasonably  expect  that  the  structure 
of  veins  in  granite,  for  instance,  will  be  similar  in 
widely  separated  mining  camps;  and  so  of  veins  in 
tou«:h  limestone,  or  easily  fissile  slates,  and  other 
characteristic  rocks;  and  we  may  take  the  generaliza- 
tion still  further,  and  expect  to  find  all  the  veins  in 
any  mining  district,  in  the  same  rock  and  belonging 
to  the  same  system,  similar  to  each  other  in  filling  as 
well  as  structure. 

But  it  does  not  follow  of  necessity  that  all  veins  in 
any  particular  region  are  of  the  same  age.  On  the 
contrary  we  frequently  find  several  systems,  each  char- 
acterized by  a  general  common  strike  and  dip,  show- 
ing that  such  regions  have  been  the  seat  of  several  fis- 
sure-forming disturbances,  which  may  have  been  of 
very  widely  varying  force,  and  followed  by  fillings  of 
a  totally  different  character;  but  usually  the  most 
strongly  developed  system  will  either  show  a  decided 
parallelism  to  the  general  direction  of  the  mountain 
range,  or  else  nearly  at  right  angles  thereto;  and,  while 
one  system  may  be  a  good  ore  producer,  another  may  be 
practically  valueless.  It  thus  early  becomes  necessary 
to  identify  their  peculiarities  and  avoid  loss. 

While  absolute  dislocation  of  the  strata  or  rocks 
may  have  been  necessary  to  produce  the  entire  series 
of  fissure  veins,  whether  parallel  to  the  strike  of  the 
rocks  or  more  or  less  at  right  angles  to  it,  simple  fold- 
ing of  the  strata  may  have  been  sufficient  to  so  far  dis- 
place the  lines  of  contact  of  two  sedimentary  rocks  as 
to  open  the  way  for  the  formation  of  contact  veins;  or 
to  so  far  rupture  a  belt  of  rocks  without  actual  dis- 
placement as  to  permit  the  formation  of  segregated 
veins  or  deposits,  or  to  rupture  horizontal  beds  of 
limestone  sufficiently  to  allow  the  percolation  of  water 
through  them,  with  the  consequent  excavation  of 
irregular  chambers. 


98  PROSPECTING  AND   VALUING  M1NEH. 

These  changes  are  common  to  all  mountain  regions, 
and  are  not  unknown  even  in  comparatively  level 
countries,  but  they  have  not  resulted  in  the  formation 
of  mineral  veins  in  all  localities.  There  are  extensive 
mountains  areas  almost  entirely  destitute  of  valuable 
mineral  deposits;  and  therefore,  while  the  preliminary 
fracturing  of  a  country  is  absolutely  essential  to  the 
formation  of  mineral  veins,  their  subsequent  filling 
with  valuable  contents  must  be  explained  by  the 
operation  of  agencies  which  were  local  in  their  action, 
and  at  the  most  very  indirectly  connected  with  the 
agencies  which  formed  the  original  fissures.  The  frac- 
turing of  the  rocks  simply  made  the  formation  of  the 
veins  possible.  The  formation  of  a  crevice  did  not 
necessarily  involve  the  formation  of  a  vein,  but  only 
governed  the  physical  aspect  of  such  a  vein  when 
formed. 


CHAPTER  VI. 

FILLING  OF  MINERAL  VEINS. 

Igneous  Theory  not  Tenable. — It  is  a  popular  idea 
that  all  mineral  veins  have  been  filled  from  below  by 
the  material  being  forced  into  them  while  in  a  molten 
condition.  This  would  involve  intense  heat.  While 
there  can  be  no  question  that  the  porphyritic  and 
basaltic  dikes  have  been  filled  in  this  manner,  a  multi- 
tude of  facts  compel  us  to  look  for  some  other  explana- 
tion for  the  majority  of  metalliferous  veins. 

That  the  intrusion  of  dikes  has  been  accompanied 
with  heat  is  abundantly  proved  by  the  changes  which 
have  been  effected  in  the  rocks  through  which  they 
pass,  or  into  and  between  which  they  have  been 
squeezed  as  sheets.  When  cutting  through  coal  beds 
or  penetrating  them,  as  in  pi.  5,  fig.  6  (after  Jukes), 
which  covers  a  length  of  nearly  1,000  ft.,  the  coal  has 
been  deprived  of  its  volatile  matter  and  becomes  what 
is  called  " blind  coal/'  or  is  even  reduced  to  a  small 
quantity  of  black  soot.  Sandstones  become  fused  into 
a  glassy  quartzite ;  slates  are  hardened  into  a  flinty  sub- 
stance with  change  of  color,  while  other  rocks  have 
become  porphyritic,  as  alongside  the  great  trachytic 
dike  which  cuts  across  Onion  Valley  in  Plumas  Coun- 
ty, Cal.  This  dike  has  a  width  of  about  30  ft.  and 
stands  up  as  a  wall  on  the  hillside  to  a  height  of  90 
ft.  in  places,  and  is  apparently  connected  with  surface 
sheets  which  overflowed  from  it.  The  country  rock  is  a 
blackish  green  slate,  but  close  to  the  dike  it  has  been 
so  altered  as  to  look  like  a  porphyry,  being  spotted 


100         PROSPECTING  AND  VALUING  MINES. 

with  white  feldspar  crystals,  which  gradually  become 
less  conspicuous  as  the  vicinity  of  the  dike  is  left,  until 
they  fade  out  entirely  in  the  plain-colored,  unaltered 
general  country  rock.  The  same  lava  flow  contains 
large  fragments  of  the  country  rock  which  have  been 
torn  from  the  sides  of  the  fissure  during  its  formation, 
and  altered  in  exactly  the  same  way,  just  as  we  con- 
vert clay  into  brick  by  the  action  of  heat.  From  these 
well  established  facts  we  would  be  justified  in  looking 
for  similar  changes  in  the  walls  of  mineral  veins,  if 
they  have  been  produced  in  the  same  way.  We  do 
find  changes  in  the  walls,  it  is  true,  produced  by  the 
action  of  heat,  but  they  are  such  as  result  from  the 
action  of  hot  water  and  steam,  and  not  of  molten  mat- 
ter. The  latter  when  once  injected  will  gradually 
cool  off,  and  when  once  cold  will  produce  no  further 
change,  while  the  hot  water  may  continue  to  circulate 
for  ages,  so  long  as  the  source  of  heat  remains  un- 
changed, and  produce  changes  much  more  extensive 
and  more  widely  disseminated  than  the  action  of 
injected  lavas. 

A  few  illustrations  may  render  the  discussion  of  this 
question  more  intelligible,  and  lead  naturally  to  the 
important  influence  which  rocks  have  on  the  nature  of 
the  vein  material. 

It  is  well  known  that  if  we  melt  copper  and  silver 
together  we  produce  an  alloy  in  which  the  silver  is  indis- 
tinguishable except  by  assay  or  analysis,  yet  in  the 
Lake  Superior  copper  mines  we  find  blotches  of  white 
silver  in  the  heart  of  solid  masses  of  native  copper  or 
crystallized  on  the  surface  of  the  copper,  showing  that 
in  the  latter  case  plainly,  and  in  the  former  by  infer- 
ence, copper  and  silver  were  deposited  in  the  vein 
alternately,  some  of  the  silver  at  least  after  the  forma- 
tion of  the  copper  had  ceased. 

At  the  Head  Center  mine,  Tombstone,  Ariz.,  crystals 
of  gold  are  found  planted  on  the  surface  of  horn  silver 
(chloride  of  silver) ;  yet  when  melted  together  gold 


FILLING  OF  MINERAL  VEINS.      '          101 

and  silver  form  an  alloy  with  the  kreatest  facility,  and 
the  affinity  of  the  metals  for  each  other  is  so  great  that 
native  gold  always  contains  more  or  less  silver. 

At  the  Alston  Moor  lead  mines  in  England,  where 
galena  in  a  matrix  or  gangue  of  fluorspar  is  worked, 
lead  crystals  (galena)  are  bedded  in  fluorspar,  with  lime 
crystals  (calcite)  planted  on  the  lead  crystals,  and 
crystals  of  "blackjack"  (zincblende)  on  the  lime 
crystals — four  minerals  superimposed  on  each  other, 
one  at  least  of  them  (zincblende)  volatile  at  a  low 
temperature  and  another  (lime)  practically  infusible. 

In  the  Sierra  Nevada  mine,  Virginia  City,  Nev. ,  a 
seam  of  broken  rock  and  clay,  which  has  been  made 
since  the  formation  of  the  vein,  is  filled  with  minute 
crystals  of  red  oxide  of  copper,  formed  by  the  coppery 
waters  which  filter  through  it  from  the  higher  levels. 

In  the  upper  part  of  the  wash  of  Furnace  creek,  on 
the  eastern  side  of  Death  Valley,  Cal.,  is  a  beautifully 
regular  vein  of  fibrous  limestone  (satin  spar)  cutting 
nearly  vertically  through  beds  of  coarse  conglomerate, 
which  show  no  signs  of  alteration  (pi.  7,  fig.  8).  Fig. 
9,  same  plate,  shows  quartz  veins  in  the  same  neigh- 
borhood and  similarly  located. 

In  the  mines  at  Batopilas,  Mexico,  native  silver 
occurs  in  veins  of  calcspar,  which  have  an  extraordi- 
nary persistence,  frequently  dwindling  down  to  a  mere 
seam,  often  less  than  1  in.  wide  for  long  distances,  and 
then  opening  out  to  a  width  of  several  feet.  In  places 
probably  90%  of  the  ore  is  crystallized  native  silver,  a 
large  proportion  of  the  remainder  being  crystallized 
ruby  silver  (arsenical)  and  crystallized  black  sulphide 
of  silver,  the  latter  often  in  branching  flakes  like  moss 
formed  in  the  joints  of  the  rock  alongside  the  veins. 

Near  Yankee  Hill,  Butfce  County,  Cal.,  beautiful 
specimens  of  crystallized  gold  are  found  in  the  joints 
of  the  porphyries,  usually  in  thin  flakes,  taking  the 
shape  of  combs,  fern  fronds,  etc.  In  this  case  there  is 
no  indication  of  veins  or  vein  matter. 


102         PROSPECTING  AND  VALUING  MINES. 

At  West  Point,  CalaveSras  Co'unty,  Gal.,  gold  occurs 
in  the  solid  granite.  At  Drytown,  Araador  County, 
Cal.,  gold  occurs  in  limestone;  and  in  Mariposa 
County,  near  Coulterville,  both  in  the  black  clay  slates 
and  serpentines.  At  Fiddletown,  in  Eldorado  County, 
gold  is  found  in  the  iron  pyrites  which  abound  in  the 
slates.  The  crystals  are  often  of  considerable  size, 
chiefly  cubes,  and  the  gold  can  be  seen  projecting 
from  the  smooth  faces  of  the  crystals. 

It  would  be  possible  to  extend  the  list  of  similar 
cases  of  crystallization  indefinitely,  but  it  is  not  neces- 
sary to  more  than  call  attention  to  the  fact  that  in 
many  cases,  if  not  in  all,  these  crystals  are  formed  in 
cavities,  many  of  them  of  such  size  as  to  be  called 
caves  or  caverns,  which  are  not  characteristic  of  any 
of  the  dikes  which  we  know  to  be  the  result  of  injec- 
tion from  below.  Good  illustrations  of  this  formation 
of  crystals  in  closed  cavities  may  be  seen  in  the  hollow 
balls  filled  with  quartz  crystals,  called  "geodes. "  The 
miners  call  the  smaller  cavities  found  in  veins  "vugs. " 

Metals  also  occur  in  gash  veins  which  must  have 
been  filled  from  the  surrounding  rocks,  having  no  con- 
nection with  the  interior  of  the  earth. 

Galena  occurs  in  irregular  deposits  in  limestone, 
where  there  is  no  evidence  of  vein  structure. 

Chrome  iron  occurs  in  isolated  masses  in  blackish- 
green  hornblende  schists;  while  platinum,  iridinm, 
osmium,  etc.,  occur  chiefly  as  grains  in  sand  or  gravel 
deposits,  which  have  probably  been  derived  from  the 
decay  of  rock  strata,  and  not  from  veins,  as  their 
occurrence  in  veins  is  unknown. 

In  the  case  of  the  "compression  veins"  in  slates,  as 
at  Amador  and  Sutter  Creek,  Cal.,  pi.  6,  fig.  1,  the  ore 
bodies,  carrying  gold,  are  often  completely  sur- 
rounded with  slates  identically  the  same  as  the  black 
clay  slates  to  the  westward  of  the  vein,  which  show  110 
trace  of  alteration  by  heat  either  as  applied  by  molten 
lava  or  hot  water,  although  they  have  been  subjected 


FILLING  OF  MINERAL  VEINS.  103 

to  immense  pressure  and  have  been  folded  in  every 
direction. 

In  Cornwall  the  remarkable  case  occurs  of  a  vein 
producing  copper  for  many  hundred  feet  in  depth, 
while  encased  in  slates  (called  "killas"),  but  chang- 
ing to  tin  when  it  passes  into  the  underlying  granite, 
as  shown  in  pi.  8  and  pi.  7,  fig.  1,  which  represent  a 
longitudinal  section  and  a  cross  section  of  the  Dol- 
coath  mine. 

Again,  we  have  those  peculiar  veins  in  which  the 
minerals  are  arranged  in  bands  parallel  to  the  walls, 
as  in  pi.  7,  fig.  4.  This  case  is  similar  to  those  in 
which  crystals  of  different  minerals  have  been 
deposited  on  the  top  of  each  other  in  succession. 

In  pi.  7,  fig.  5.,  we  have  a  case  in  which  a  band  of 
rock  has  been  altered,  and  contains  more  or  less 
parallel  ore  bodies  (shown  in  black),  with  numerous 
threads  and  stringers  connecting  them,  the  whole 
"•stockwork"  fading  out  into  the  inclosing  rock  with- 
out any  positive  definition  or  walls. 

Many  other  cases  of  interest  might  be  cited,  but  these 
are  sufficient  to  show  the  difficulties  which  surround  the 
theory  of  igneous  filling  of  mineral  veins  from  below 
by  injection  in  the  form  of  molten  or  pasty  matter. 

In  the  case  of  the  limestone  deposits  there  is  no  con- 
nection by  well  defined  fissures  wich  the  interior  of 
the  earth,  through  which  the  filling  could  have  taken 
place;  and  in  the  case  of  the  Batopilas  mines  it  is  in- 
conceivable that  a  mineral  so  infusible  as  limespar 
could  have  been  injected  into  fissures,  frequently  less 
than  an  inch  in  width;  while  if  we  admit  the  possi- 
bility of  the  lime  being  fused,  the  heat  would  have 
been  so  intense  that  the  adjacent  rocks  would  have 
been  fused  into  lava,  and  the  minerals  found  in  the 
injected  material  would  have  been  volatilized  and 
entirely  eliminated,  unless  retained  by  condensation 
in  the  cooler  surface  rooks,  in  which  case  the  ores 
would  be  found  only  near  the  surface  and  in  the  coun- 


104         PROSPECTING  AND  VALUING  MINES. 

try  rock  as  well  as  in  the  lode,  and  the  latter  would  be 
barren  or  unproductive  in  depth,  which  from  actual 
exploration  we  know  is  not  the  case.  That  heat  does 
operate  in  this  way  we  know  from  the  quicksilver 
mines  of  Lake  County,  Cal.,  where  the  surface  rocks 
are  filled  with  minute  globules  of  mercury,  which  have 
been  brought  up  from  below  by  the  action  of  hot 
springs  and  steam,  and  condensed  near  the  surface, 
where  the  temperature  fell  below  the  volatilizing  point 
of  the  mercury. 

Similar  difficulties  meet  us  in  the  case  of  the  lime 
vein  on  Furnace  Creek,  and  indeed  in  all  cases  where 
minerals  occur  intimately  associated  with  limestone, 
either  in  the  body  of  the  rock  itself,  or  in  the  crevices, 
or  where  it  becomes  the  gangue  accompanying  the  ore. 

The  occurrence  of  gold  in  porphyry,  slate,  lime, 
granite  and  serpentine,  outside  of  veins,  is  also  inex- 
plicable on  the  theory  of  upward  injection  ;  as  also  the 
presence  of  minerals  in  gash  veins  and  the  slates  Of 
the  mother  lode  in  California. 

The  same  appears  patent  of  all  those  cases  where 
minerals  are  found  which  readily  form  alloys  and  have 
a  similar  melting  point,  in  close  contact,  yet  each  re- 
taining its  individual  character;  as  well  as  in  all  cases 
of  superimposed  crystals  lining  cavities  or  vugs  in  the 
vein,  especially  where  the  cavities  are  of  such  dimen- 
sions as  to  become  worthy  of  the  name  of  caves. 

That  crystals  do  form  in  dikes  or  veins  of  igneous 
(or  rather  of  plutonic)  origin  is  not  denied;  but  they 
form  a  compact  mass,  the  various  minerals  crowding 
each  other  to  distortion,  and  mixed  in  tolerably  uni- 
form proportions,  as  in  granite  and  the  porphyries,  in 
which  cavities  are  almost  unknown;  while  such 
crystals  as  they  do  yield  outside  of  the  mass  are  found 
in  crevices  formed  at  a  later  date  than  the  origin  of 
the  rock. 

We  have  still  the  case  of  the  Cornish  veins,  which  is 
only  a  type  of  many  others,  where  the  imagination  can 


FILL  I  NO  OF  MINERAL   VEINS.  105 

hardly  realize  how  a  vein  can  be  filled  from  below, 
during  the  same  operation,  with  copper  in  its  upper 
portion  and  tin  in  its  lower,  and  why  the  change  in 
the  character  of  the  injected  material  should  have 
taken  place  just  at  the  junction  of  the  two  rocks  which 
were  traversed  by  the  fissure. 

In  such  cases  as  the  occurrence  of  flakes  of  horn 
silver  in  the  joints  of  quartzites  at  the  Isabel  mine, 
near  Globe,  Ariz.,  which  can  be  scraped  off,  leaving 
thequartzite  absolutely  barren  of  silver;  and  the  same 
ore  in  the  joints  of  limestone  west  of  Tucson,  Ariz., 
where  the  surface  of  the  joints  gives  good  assays, 
while  the  silver  penetrates  the  blocks  of  limestone  in 
steadily  diminishing  quantities  for  only  a  few  inches, 
leaving  their  interior  entirely  innocent  of  ore,  we  can- 
not invoke  the  igneous  theory,  because  there  are  no 
veins  to  be  injected. 

The  same  may  be  said  of  the  horn  silver  found  in 
the  Leeds  mine,  near  the  southeast  corner  of  Nevada, 
which  in  many  respects  is  one  of  the  most  remarkable 
occurrences  of  silver  on  record.  There  is  no  true 
vein;  the  matrix  or  gangue  in  this  case  is  a  nearly 
horizontal  bed  of  sandstone,  in  which  are  found  large 
quantities  of  vegetable  remains,  such  as  wood,  twigs 
and  leaves,  and  it  is  these  which  carry  chloride  of 
silver  in  quantity  sufficient  to  make  working  of  the 
mass  not  only  possible  but  profitable.  In  this  case 
there  cannot  be  a  suspicion  of  injection. 

More  doubt  hangs  over  the  silver  ores  in  the 
trachytes  or  rhyolites  of  the  Calico  district,  San  Ber- 
nardino County,  Cal.,  which  occur  in  the  crevices  of  a 
truly  eruptive  rock;  but  even  here  the  ores  may  lie  in 
fissures  formed  subsequently  to  the  eruption  of  the 
trachyte. 

We  are  thus  compelled  to  look  for  some  other 
method  by  which  the  fissures,  now  called  veins,  have 
been  filled  with  their  mineral  constituents.  Among 
those  familiar  with  the  subject  the  igneous  theory, 


106         PROSPECTING  AND  VALUING  MINES. 

which  held  sway  for  many  years,  has  been  generally 
abandoned  as  incapable  of  explaining  the  greater  por- 
tion of  the  phenomena. 

Aqueous  Theory. — The  distribution  of  ore  in  veins 
is  of  the  most  irregular  character.  In  some  of  the 
gold  veins  of  California  the  metal  is  collected  in  well- 
defined  pockets,  containing  all  the  way  from  a  few 
pounds  up  to  half  a  million  dollars,  surrounded  by 
barren  white  quartz  in  immense  quantities.  In  other 
mines  we  find  the  ore  in  threads  and  stringers,  more  or 
less  parallel  to  the  general  direction  of  the  walls,  fad- 
ing out  into  the  country  rock  which  evidently  forms 
the  general  mass  of  the  vein,  in  fact  constituting"  its 
gangue.  These  and  other  allied  facts  suggest  the 
modern  explanation,  which  attributes  the  filling  of 
veins  to  the  circulation  of  heated  waters  in  the  earth's 
crust. 

Distribution  of  Metals,  etc.,  in  Nature. — Of  late  years 
researches  into  the  constitution  of  sea  and  min- 
eral waters  has  revealed  the  presence  in  them  of  a  long 
list  of  elements  in  the  form  of  salts,  establishing  the 
fact  of  their  solubility  in  nature  as  well  as  in  the 
chemist's  laboratory.  In  mineral  waters  the  metals  iron, 
arsenic,  lithium,  csesium,  rubidium,  copper,  zinc  and 
manganese  have  been  detected,  along  with  the  elements 
of  earthy  minerals  which  form  the  gangue  of  veins, 
such  as  silica,  magnesia,  lime,  alumina,  fluorine  and 
baryta;  besides  soda,  patash,  boron,  chlorine,  iodine, 
bromine,  phosphorus  and  sulphur,  many  of  which 
latter  form  salts  which  are  excessively  soluble. 

Sea  water,  according  to  Prof ,  Forchhammer,  in  addi- 
tion to  the  chlorides  and  sulphates  of  sodium,  mag- 
nesium, potassium  and  calcium,  contains  silica,  boric 
acid,  bromine,  iodine,  fluorine  as  acid,  and  the  oxides 
of  nickel,  cobalt,  manganese,  aluminum,  zinc,  silver, 
lead,  copper,  barium  and  strontium;  and  arsenic, 
gold,  lithium,  rubidium,  and  csesium  have  been  dis- 
covered since  Forchhammer  wrote.  The  experiments 


FlLLltfQ  OF  MINERAL   VEINS.  107 

of  Prof.  Liversidge  on  the  sea  water  off  the  coast  of 
Australia  give  positive  results  as  to  the  presence  of 
gold.  Other  investigators  also  have  detected  gold  in 
sea  water. 

Daintree  reports  the  occurrence  of  gold  in  the  ser- 
pentines and  pyritic  diorites  of  Queensland,  and  the 
pyritic  granites  of  New  South  Wales. 

The  nodules  or  concretions  of  manganese  dredged 
from  the  ocean  floor  by  the  Challenger  expedition 
showed  the  presence  of  nickel  and  cobalt. 

Prof.  F.  Sandberger  has  announced  the  discovery  of 
small  quantities  of  silver,  lead,  copper,  nickel,  cobalt, 
bismuth,  arsenic,  antimony  and  tin,  in  silicates  such 
as  olivine,  augite,  horneblende  and  mica,  which  are 
constituents  of  igneous  rocks. 

Prof.  Dana  records  the  occurrence  of  nickel  in  the 
Vesuvian  lavas,  and  also  the  chlorides  of  lead,  copper, 
iron  and  manganese,  as  forming  on  the  lavas  at  the 
craters  from  the  heated  vapors;  and  similar  results 
would  probably  be  obtained  at  other  volcanoes  had 
they  been  as  carefully  studied.  He  also  notes  the 
presence  in  minerals  which  form  a  portion  of  gneiss 
and  granite,  of  manganese,  lithium,  cerium,  lantha- 
num, didymium,  yttrium,  zinc,  berylinm,  titanium, 
molybdenum  and  cobalt;  the  latter  metal  also  in 
mica  schists  with  arsenic. 

J.  S.  Curtis  determined  the  presence  of  gold  and 
silver  in  the  silicates  of  the  rocks  adjacent  to  the  Corn- 
stock  lode,  the  silver  chiefly  in  those  of  the  hanging 
wall  diabase  or  porphyry  and  the  gold  in  those  of  the 
foot  wall  syenite;  and  when  writing  on  the  quicksilver 
deposits  of  the  Pacific  coast  of  the  United  States, 
Prof.  G.  F.  Becker  reports  the  presence  of  antimony, 
arsenic,  lead  and  copper  in  the  underlying  granites 
at  Steamboat  Springs,  Nev. ;  and  records  the  fact  that 
these  springs  are  to-day  depositing  quicksilver,  gold, 
antimony,  arsenic,  lead  and  copper. 

Daubree  gives   the  following  list  of   elements,  ar- 


108         PROSPECTING  AND   VALUING  MINES. 

ranged  somewhat  in  the  degree  of  their  importance 
(Maskelyne  adds  lithium  and  antimony):  iron,  mag- 
nesium, silicon,  oxygen,  nickel,  cobalt,  chromium, 
manganese,  titanium,  copper,  aluminum,  potassium, 
sodium,  calcium,  arsenic,  phosphorus,  nitrogen,  sul- 
phur, chlorine,  carbon  and  hydrogen,  several  of  the 
compounds  of  which  are  peculiar  to  meteorites.  The 
majority  of  the  meteoroids  with  which  the  earth 
comes  in  contact  are  exceedingly  small,  and  a  weight 
of  1,000  Ib.  is  probably  uncommon,  but  when  the 
daily  number  encountered  by  the  earth,  estimated  at 
20,000,000,  is  multiplied  by  years  and  centuries  it  is 
evident  that  the  addition  of  their  contained  minerals 
to  the  earth's  surface  is  worthy  of  notice.  These 
minerals,  forming  part  of  the  sedimentary  strata,  could 
find  their  way  into  veins  without  even  the  intervention 
of  volcanic  agency.  It  is  more  than  probable  that  the 
cobalt-nickel-manganese  nodules  of  the  deep  sea  are 
derived  from  the  meteoric  dust  falling  on  its  surface. 

Outside  of  the  eruptive  rocks  we  find  ore  minerals 
disseminated* in  secondary  or  stratified  rocks,  such  as 
slates  and  sandstones,  as  well  as  in  limestones,  and  it 
is  from  all  of  these  sources  combined  that  the  metals 
have  been  concentrated  into  veins. 

Underground  Circulation. — It  is  evident  that  water 
is  the  active  factor  in  all  these  changes.  We  must 
remember  that  a  considerable  portion  of  the  water 
which  falls  upon  the  surface  of  the  earth  does  not  pass 
off  promptly  into  the  rivers,  but  is  absorbed  by  the 
earth  and  rocks,  and  by  the  action  of  gravity  pene- 
trates to  depths  practically  unknown.  Of  this  we 
have  absolute  demonstration  from  its  presence  in  the 
quartz  crystals  of  deep-origined  eruptive  rocks,  as 
numerous  but  exceedingly  small  bubbles,  only  visible 
under  a  powerful  microscope;  and  from  the  enormous 
volumes  of  steam  which  are  given  off  by  volcanoes  in 
eruption,  and  which  continue  to  be  evolved  from  the 
lavas  after  their  ejection.  We  must  not  imagine  the 


FILLING  OF  MINERAL  VEINS.  109 

crust  of  the  earth  as  a  solid  mass,  through  only  the 
crevices  of  which  water  may  find  a  passage;  there  is 
abundant  evidence  that  every  particle  of  the  earth's 
crust  to  depths  of  which  we  have  any  knowledge,  and 
presumably  far  below,  is  charged  with  water,  and  that 
there  is  no  substance  known  which  is  not  permeable 
by  it.  Under  pressure  it  can  be  forced  through  iron, 
appearing  as  a  perspiration  on  the  outer  surface  of 
the  confining  flask,  and  with  such  a  practical  demon- 
stration we  are  compelled  to  admit  the  fact  as  stated. 

Heat. — While  this  water  at  the  surface  may  be  cold, 
we  know  from  the  evidence  of  borings  and  mining 
works  that  the  temperature  increases  with  depth  from 
that  point  near  the  surface  at  which  it  remains  sta- 
tionary through  summer  and  winter  alike,  so  that  in 
the  Comstock  lode,  at  the  2,300-ft.  level  of  the  C.  &  C. 
shaft,  the  thermometer  registered  about  150°  F.,  and 
at  the  3,000-ft.  level  of  the  Yellow  Jacket  shaft  170°. 
There  is  no  difficulty  in  imagining  this  temperature 
increasing  to  the  boiling  point  of  water  (212°)  and 
rising  greatly  higher,  until  it  becomes  so  intense  that 
the  water  may  be  said  to  be  (l white  hot."  This  heat 
is  not  the  product  of  actual  fires.  It  may  be  partly 
caused  by  chemical  action,  but  is  more  extensively 
due,  in  all  probability,  to  the  pressure  on  the  earth's 
crust  caused  by  its  steady  and  constant  contraction  as 
it  cools,  and  to  the  friction  from  the  wrinkling  move- 
ments, The  rocks  become  hot  during  compression  and 
movement  and  impart  their  heat  to  the  contained 
water,  which,  aided  by  hydrostatic  pressure,  brings 
it  to  the  surface  and  it  is  dissipated  in  hot  springs; 
or,  if  such  a  vent  is  not  made,  by  volcanic  eruptions, 
or  the  intrusion  of  lava  into  upper  and  colder  strata. 

Solution,  Transportation  and  Deposition. — We  are 
now  prepared  to  understand  the  action  of  water  in  the 
subsequent  processes.  We  have  the  waters  penetrat- 
ing the  rocks  everywhere,  the  cooler  waters  descend- 
ing, the  heated  ones  tending  to  rise,  or  being  forced 


HO         PROSPECTING  AND  VALUING  MINES. 

to  the  surface  along  the  lines  of  least  resistance,  such 
as  the  fault  fissures,  by  the  pressure  of  other  waters  or 
steam. 

The  ability  of  water  to  decompose  rocks  depends  on 
the  presence  of  carbonic  acid  and  alkaline  material 
such  as  the  carbonates  of  soda  and  potash,  and  its 
solvent  powers  are  increased  with  a  rise  of  tempera- 
ture. Its  first  carbonic  acid  is  derived  by  rain  water 
from  the  atmosphere,  and  the  moment  it  touches  the 
earth  it  begins  its  work  of  decomposition  and  rear- 
rangement, picking  up  and  dissolving  one  mineral  and 
depositing  another.  Water  traversing  an  open  fissure 
would  thus  leave  a  portion  of  its  contents  on  the  walls, 
both  sides  alike,  as  it  gradually  cooled  in  its  ascent, 
just  as  sugar  candy  will  crystallize  out  of  the  sugar 
solution  as  it  is  cooled  or  evaporated,  the  process  of 
cooling  producing  the  same  result  as  that  of  evapora- 
tion, in  both  cases  the  liquid  being  unable  to  carry  so 
great  a  load  drops  it  at  the  first  opportunity.  In  this 
manner  have  veins  like  those  of  the  Wheal  Mary  Ann 
lode  in  Cornwall  been  formed  (pi.  7,  fig.  4),  a,  being 
chalcedony  (silica  combined  with  water),  b,  glassy 
quartz  terminating  in  crystals;  c,  galena;  and  the 
central  core  d,  chalytite  (carbonate  of  iron),  the  depo- 
sition on  both  walls  being  similar  and  indicating  the 
origin  of  the  minerals.  The  change  in  the  deposited 
mineral  maj'  have  taken  place  either  because  of  the 
exhaustion  of  the  locality  from  which  it  had  been  col- 
lected by  the  water,  or  from  such  divergence  in  the 
course  of  the  underground  flow  by  disturbances  like 
earthquakes  that  the  material  was  drawn  from  a  new 
series  of  rocks.  A  similar  incrustation  of  small  cavi- 
ties by  waters  abounding  in  silica  has  formed  agates, 
the  banding  being  due  to  the  changing  presence  of 
the  coloring  material.  Compact  and  close-grained  as 
these  agates  may  seem,  they  are  in  reality  porous,  for 
it  has  for  centuries  been  a  common  practice  to  boil 
them  in  suitable  materials  to  increase  the  brilliancy  of 


FILLING  OF  MINERAL  VEINS.  Ill 

the  coloring  of  the  bands,  the  change  being  due  to  the 
partial  absorption  of  the  material  with  which  they 
have  been  treated.  When  the  cavity  has  not  been 
completely  filled,  it  is  either  left  with  a  smooth  sur- 
face of  chalcedony  (which  does  not  crystallize)  or 
lined  with  crystals  of  quartz,  calcite,  etc.  In  such 
manner  also  have  opals  and  other  minerals  been  intro- 
duced into  the  oval  cavities  of  basaltic  lavas,  and  thus 
we  have  also  an  explanation  of  how  minerals  can  be 
deposited  as  crystals  on  the  top  of  each  other  by  just 
such  changes  in  the  character  of  the  circulating  waters. 
Source  of  the  Ore. — The  source  of  the  minerals  thus 
deposited  is  to  be  found  in  the  country  rocks  of  the 
region,  mainly  the  eruptives,  which,  as  we  have  seen, 
contain  nearly  all,  and  probably  would  be  shown  to 
contain  quite  all,  of  those  known;  or  even  from  the 
secondary  or  stratified  rocks  derived  'from  older 
igneous  rocks,  into  which  the  mineral  constituents  of 
the  latter  must  unquestionably  have  been  carried  dur- 
ing their  deposition  as  sediment.  That  lavas  have 
been  deprived  of  their  valuable  mineral  constituents 
in  this  way  is  fairly  proved  by  the  experiments  of 
Prof.  Becker  and  Dr.  Carl  Barus,  on  the  Comstock. 
The  hanging  wall  of  that  lode  is  diabase  (in  Virginia 
City),  known  by  the  miners  as  "blue  porphyry/'  a 
term  which  well  expresses  its  appearance  when  freshly 
broken.  The  Sutro  tunnel  has  exposed  the  structure 
of  the  east  country  (that  is,  on  the  hanging  wall  side) 
for  more  than  three  miles,  and  developed  a  series  of 
bands  showing  plainly  the  results  of  solfataric  action 
(by  heated  waters),  with  alternating  bands  of  hard 
blue  porphyry.  Outside  of,  and  next  to  the  lode,  the 
rock  is  hard  and  suggestive  of  no  change,  except  by 
the  presence  of  iron  pyrites,  which  is  nearly  always  a 
product  of  decomposition,  but  under  the  microscope 
it  becomes  evident  that  extensive  changes  have  taken 
place  in  it.  Its  crystalline  structure  has  been  modi- 
fied, the  hornblende  and  augite  (silicates)  have  been 


112         PROSPECTING  AND  VALUING  MINE8. 

altered,  pyrite  Laving  been  made  out  of  their  iron, 
and  the  silver  which  is  present  in  them  further  away 
from  the  lode  has  disappeared,  the  natural  conclusion 
being  that  it  has  found  its  way  into  the  lode  through 
water. 

Form  of  Deposit. — All  veins  were  not  formed  in  the 
manner  described  as  occurring  at  the  AVheal  Mar}r  Ann 
lode  and  others  similarly  constituted.  This  presup- 
poses an  open  fissure,  and  it  does  not  seem  possible 
that  all  fissures  in  which  veins  have  been  formed  re- 
mained open  during  the  process.  In  many  it  is  plain 
that  such  was  not  the  case,  because  they  show  no  true 
walls,  as  in  the  Great  Flat  lode,  Cornwall  (pi.  7,  fig. 
5,  and  pi.  6,  fig.  3),  where  the  ore  B  is  frozen  to  the 
dike  A,  and  there  is  only  one  wall;  or  in  pi.  6,  fig.  1, 
where  the  masses  are  lenticular  and  not  connected 
with  each  other  (Keystone  mine,  Cal.);  or  in  pi.  6, 
fig.  2,  where  there  is  no  trace  of  banding,  and  the 
hanging  wall  shows  many  feeders  or  stringers  not 
seen  on  the  foot  wall.  The  maintenance  of  an  open 
fissure  in  the  case  of  such  a  structure,  as  pi.  2,  fig.  2  (a 
generalized  cross  section  of  the  Comstock  lode  in  Vir- 
ginia City),  would  have  been  an  impossibility  for  the 
three  or  four  miles  of  its  length,  the  foot  wall  having 
a  dip  of  only  40°;  but  it  is  equally  plain  that  a  slight 
sliding  of  the  hanging  wall  on  the  foot  would  produce 
just  such  cracks  as  a,  b,  c,  d,  accompanied  by  an  im- 
mense amount  of  broken  material.  In  many  such  cases 
there  is  no  true  gangue,  the  ore  occurring  in  the  orig- 
inal country  rock,  decomposed  it  is  true,  in  bands  or 
stringers  more  or  less  parallel  to  the  walls,  or  strike 
of  the  rocks  which  have  undergone  decomposition,  but 
fading  out  into  the  unaltered  country  rock  on  either 
side  as  at  the  Great  Flat  lode,  or  only  on  one  side,  as 
in  pi.  6,  fig.  3;  while  in  fig.  1  there  is  one  true  wall  at 
the  contact  line.  In  these  cases  we  can  only  account 
for  the  presence  of  ore  on  the  supposition  that  as  the 
percolating  water  dissolved  and  carried  away  the  par- 


FILLING  OF  MINERAL   VEINS.  113 

tides  of  the  rock  it  left  in  their  place  particles  of  ore, 
simply  making  an  exchange,  and  it  can  easily  be 
understood  how  this  substitution  would  go  on  most 
rapidly  and  most  extensively  in  those  portions  of  the 
fissure  which  had  been  most  shattered  during  its  forma- 
tion, as  the  material  would  have  been  more  largely 
ground  into  powder  at  such  points,  not  only  allowing 
more  water  to  find  its  way  through  those  portions,  but 
presenting  vastly  greater  surfaces  to  the  action  of  the 
water.  Thus  a  cube  with  faces  1  in.  square  has  a 
surface  as  6  to  1  of  bulk,  while  a  cube  with  faces  2  in. 
square  has  a  surface  of  only  3  to  1  compared  with  bulk. 
It  is  at  such  places  that  the  largest  deposits  have  taken 
place,  and  it  is  thus  that  "horses"  have  usually  been 
formed  in  the  lodes;  not  by  masses  falling  into  an 
open  fissure,  but  by  the  water  circulating  through 
crevices,  completely  surrounding  a  block  of  country 
rock.  We  constantly  find  pieces  of  country  rock  in 
veins  completely  inclosed  in  ore,  and  these  are  only 
horses  on  a  very  small  scale.  The  Savage  mine,  at 
Virginia  City,  afforded  abundant  specimens  of  min- 
eralized porphyry,  suggesting  this  origin,  and  those 
of  Monte  Cristo,  Wash.,  offer  many  more  illustrations 
which  are  totally  inexplicable  on  any  theory  of  large 
open  fissures.  Many  such  veins  have  acquired  slicken 
sides  and  gouge  by  subsequent  movements  of  the  rocks, 
which  would  naturally  follow  such  lines  of  weakness, 
and  may  even  have  undergone  a  partial  refilling  and 
reconcentration  of  their  own  constituents,  some  por- 
tions having  been  impoverished  to  enrich  others.  That 
such  movements  have  taken  place  is  shown  by  the 
crushing  of  the  quartz  in  some  of  the  larger  bodies  on 
the  Comstock  lode,  so  that  it  was  known  to  the  miners 
as  "sugar  quartz." 

These  examples  suggest  an  explanation  which  will 
account  for  nearly  all  cases  of  vein  structure,  and  at- 
tention in  the  field  will  show  how  beautifully  the 
cycle  of  changes  is  constantly  in  progress,  beginning 


114         PROSPECTING  AND  VALUING  MINES. 

with  the  earliest  fracturing  of  the  rocks  and  the  first 
rainfall,  with  no  cessation  to  the  present  time. 

Rationality  of  Natural  Processes. — A  moment's 
thought  will  show  that  under  any  circumstances  some 
such  results  as  have  been  outlined  must  have  been  the 
outcome  of  the  surface  changes  of  the  earth.  Even 
had  the  original  veins  been  solid  masses  of  gold, 
silver,  copper,  etc.,  their  contents  would,  as  they  were 
worn  away,  have  been  scattered  far  and  wide  through 
the  rocks  which  were  formed  out  of  the  earth's  first 
crust,  even  if  that  crust  itself  did  not  contain  them, 
and  the  condition  of  the  rocks  which  we  have  pictured 
would  have  been  one  of  the  first  results  of  erosion, 
and  the  formation  of  veins  by  segregation  or  substitu- 
tion must  have  commenced  even  in  those  early  days, 
by  the  workings  of  the  laws  of  chemical  affiuit3r,  which 
imply  the  abandonment  by  one  element  of  its  associate 
in  a  compound  when  it  meets  with  another  which  is 
more  to  its  liking  under  suitable  conditions  for  mak- 
ing the  exchange. 

How  easily  these  changes  are  effected  may  be  seen 
in  the  occasional  action  of  metallic  compounds  in  the 
cabinet.  Just  as  the  iron  pyrite  crystals,  so  abun- 
dant in  some  of  the  gravel  mines  of  California  (pi.  11, 
fig.  3,  shows  a  petrified  tree  covered  with  them),  drop 
to  pieces  and  decay  with  extraordinary  rapidity,  so 
specimens  of  pyrite  of  the  bronze-colored  variety  from 
the  Glacier  mine,  Monte  Cristo  district,  Wash.,  after 
remaining  in  the  writer's  cabinet  only  two  months, 
were  entirely  decomposed,  the  pyrites  having  absorbed 
moisture,  which  combining  with  the  contained  sul- 
phur had  produced  sulphuric  acid,  which  in  its  turn 
had  combined  with  the  gangue  of  the  specimen  (par- 
tially altered  porphyry),  forming  glistening  salts  and 
rough  concretions,  not  only  on  the  specimen  originally 
attacked,  but  on  the  adjacent  ones  which  happened  to 
be  in  contact  with  it,  however  slightly.  The  amount 
of  moisture  absorbed  was  so  great  that  what  remained 


FILLING  OP  MINERAL  VEINS.  115 

of  the  specimens  could  not  be  handled  without  stain- 
ing the  hands  black.  On  seeing  the  change  the  writer 
remembered  extracting  from  the  same  vein,  in  a  prev- 
ious year,  samples  with  the  same  appearance,  having 
undergone  the  same  changes  in  place.  If  then  the 
small  amount  of  moisture  which  is  present  in  a  dwell- 
ing room  can  effect  such  changes,  we  are  at  no  loss  to 
understand  how  much  greater  ones  can  be  effected  by 
nature  in  her  vast  underground  workshops,  with  her 
absolute  disregard  of  the  element  of  time. 

Ore  Deposit*  in  Limestone. — In  a  somewhat  similar 
way  have  the  greater  portion  of  the  deposits  in  lime- 
stone been  formed,  percolating  waters  eating  out  pas- 
sages and  chambers,  which  have  been  subsequently 
filled  with  iron,  lead  or  zinc  ores  by  the  waters  trav- 
ersing them.  The  ability  of  water  to  excavate  caves, 
such  as  the  Mammoth  Cave  in  Kentucky,  and  hundreds 
of  others  in  all  extensive  limestone  regions,  is  so  well 
known  as  to  require  no  further  comment,  except  that 
the  most  remarkable  feature  about  them  is  their  sub- 
sequent filling  with  large  bodies  of  mineral,  usually 
of  only  one  or  two  kinds,  much  less  complex  in  their 
constitution  than  the  filling  of  veins;  which  suggests 
a  different,  probably  cooler,  condition  of  the  percolat- 
ing water.  Such  deposits  are  of  the  most  irregular 
shape,  due  to  the  vagaries  of  the  water  which  hol- 
lowed out  the  chambers,  and  when  the  walls  are 
reached  they  may  generally  be  scraped  clean,  as  the 
mineral  does  not  usually  penetrate  the  limestone  to 
any  depth.  PI.  6,  fig.  8,  is  a  sketch  of  such  a  deposit 
formed  in  limestone,  on  the  bedding  planes  and  joints, 
and  controlled  only  by  the  lines  of  flow  of  the  water, 
as  indicated  by  the  arrowheads.  Such  are  the  deposits 
of  Wisconsin  and  Illinois.  Fig.  4,  same  plate,  shows 
the  limestone  traversed  by  the  dike  B,  and  the  arrow- 
heads the  possible  direction  of  the  water  flow,  which 
if  descending,  as  at  A,  might  form  ore  bodies  as  shown 
in  black,  or  if  ascending,  as  at  (7,  either  as  hot  or  cold 


116         PROSPECTING  AND  VALUING  MINES. 

water  under  pressure  would  present  a  similar  structure. 
Fig  7  shows  the  structure  of  the  veins  at  Tombstone, 
Ariz.,  being  successive  strata  of  slates  S,  limestone,  L, 
quartzite,  Q,  and  dolomite  (magnesian  limestone)  D, 
traversed  by  the  quartzose  fissure  veins  A.B,  which 
are  connected  in  the  limestone  by  the  flat  bodies  of 
rich  lead  ore,  C.  In  pi.  1,  fig.  2,  we  have  at  Leadville, 
Colo.,  lead  ores  lying  between  the  limestone  flour,  the 
deposits  being  nearly  horizontal,  and  porphyries  for 
a  roof. 

On  pi.  7,  fig.  2,  we  have  hematite  B,  deposited  in 
cavities  of  the  mountain  limestone  A,  at  Ulverstone, 
England.  Subsequent  to  the  deposition  of  the  ore  it 
is  evident  that  a  further  portion  of  the  limestone  was 
dissolved  by  waters  free  from  iron,  forming  a  later  cave 
which  was  filled  with  the  clay  G,  the  whole  being 
probably  partially  worn  away  before  the  covering  of 
dirt  D  was  laid  down  at  a  much  later  date.  In  fig.  3, 
same  plate,  we  have  a  similar  formation  at  Al  ten  berg, 
Germany,  only  calamine  (silicate  of  zinc)  takes  the 
place  of  the  hematite  in  the  former  illustration.  B  is  a 
body  of  limestone,  lying  between  the  slates  A,  the 
zinc  ore  D  filling  a  cavity  of  erosion,  and  the  clay  C 
filling  a  cavern  of  later  date  formed  after  the  deposi- 
tion of  zinc  ore  had  ceased. 

In  most  such  cases  it  is  probable  that  the  filling 
took  place  by  waters  percolating  through  rocks  of  later 
formation,  lying  above  the  limestone  in  which  the 
caverns  were  formed,  from  which  they  abstracted  the 
iron  and  zinc,  only  to  redeposit  them  when  presented 
with  a  more  tempting  morsel  in  the  shape  of  lime. 

Ores  Possibly  Derived  Directly  from  the  Sea. — 
Most  chloride  and  bromide  ores  of  silver  and  lead 
are  found  near  the  surface,  in  the  joints  of  limestones 
and  quartzite;  it  is  very  probable  that  such  rocks  have 
derived  the  ore  found  in  them  from  sea  water,  when 
they  were  a  portion  of  the  ocean  bottom.  In  Arizona 
there  are  many  occurrences  of  these  ores  in  localities 


THE  FILLING  OF  MINERAL   VEINS.  117 

where  such  a  condition  has  been  possible,  there  being 
evidences  of  the  former  existences  of  an  ancient  inland 
sea.  A  similar  explanation  is  advanced  to  account  for 
some  gold-bearing  conglomerates,  in  which  the  gold  is 
supposed  to  have  been  precipitated  from  the  ocean, 
near  shore.  By  a  secondary  process  the  gold  sparsely 
disseminated  in  mud  beds  at  the  bottom  of  the  sea 
might  be  concentrated  in  quartz  veins,  traversing  the 
shales  and  slates  formed  by  the  consolidation  of  these 
beds.  The  ocean-formed  ore  bodies  would,  if  derived 
directly,  be  beds  or  impregnations  and  not  true  veins. 

Electro-chemical  Action. — Around  many  of  these 
phenomena,  as  around  so  many  of  the  operations  of 
nature,  there  hangs  a  suspicion  of  the  intervention  of 
electricity.  The  action  of  electrical  currents  is  forci- 
bly suggested  in  the  case  of  native  copper  mixed 
with  native  silver,  or  of  gold  crystals  deposited  upon 
horn  silver;  but  even  if  such  an  agency  was  active  in 
their  production  there  must  have  been  a  previous 
leaching  of  other  rocks  to  provide  the  solutions  from 
which  the  metals  were  reduced  and  crystallized. 

A  Cycle  of  Perpetual  Change. — That  operations  such 
as  we  have  been  describing  are  constantly  going  on  in 
nature,  and  that  no  extraordinary  processes  need  be 
invoked  to  account  for  the  phenomena  we  see,  is  plainly 
evident  from  the  changes  which  take  place  in  the 
outcrops  of  veins  and  elsewhere.  We  constantly  find 
incrustations  of  various  salts,  such  as  alum  and  those 
of  soda  and  potash,  forming  on  the  sides  of  caves,  and 
even  of  other  minerals  on  the  walls  of  deserted  mines; 
we  secure  copper  from  the  waters  discharged  by  copper 
mines  or  mines  of  coppery  iron  pyrite  by  allowing  it 
to  run  over  scrap  iron,  which  is  destroyed  by  the  acid 
in  the  water  and  copper  released ;  the  pyrite  in  the 
outcrop  of  veins  is  decomposed  under  the  joint  action 
of  air  and  water,  leaving  a  deposit  of  rusty  iron- 
stained  gaugne,  while  the  sulphuric  acid  percolates 
downward  to  produce  other  changes;  we  find  surface 


118         PROSPECTING  AND   VALUING  MINES. 

pyrites  likewise  decomposing,  parting  with  their  sul- 
phur and  iron,  only  to  combine  with  oxygen,  and  form 
the  red  and  black  oxides  of  copper,  which  are  richer 
than  the  original  ore,  and  in  fact  are  merely  concen- 
trates of  ores  which  may  even  be  too  poor  to  work 
when  the  limits  of  the  changes  are  reached,  which  is 
usually  where  the  presence  of  permanent  water  pre- 
vents contact  with  the  air.  We  also  find  that  many 
carbonates  of  lead  have  a  core  of  galena,  which  is  the 
sulphide,  and  know  that  the  conversion  has  taken 
place  since  the  deposition  of  the  galena ;  and  if  we 
look  carefully  around  us  we  will  meet  everywhere  with 
alterations  going  constantly  forward.  Brought  up 
from  the  unknown  interior  of  the  earth  by  lavas,  the 
minerals  are  collected  from  them  into  veins,  only  to 
be  again  scattered  as  the  veins  are  worn  away  in  the 
general  destruction  of  the  earth's  surface,  and  mingled 
with  the  fragments  of  the  lavas  in  sedimentary  de- 
posits, which,  as  we  have  seen,  ultimately  return  to 
granite,  only  to  be  intruded  into  the  overlying  strata, 
the  wearing  away  of  which  uncovers  the  granite,  and 
the  circle  is  completed.  Formation,  rearrangement, 
destruction,  reformation  and  return  to  the  original  are 
the  perpetual  cycle  of  the  changes  in  veins,  and  not 
only  of  them  but  of  the  rocks  in  which  they  are  con- 
tained. 

Local  Limitations. — These  views  afford  a  natural 
explanation  of  the  reason  why  mineral  veins  are  con- 
fined to  certain  regions  and  are  not  found  in  all  areas 
of  dislocation.  We  have  no  knowledge  of  the  appear- 
ance of  the  original  crust  of  the  earth,  as  it  was 
formed  under  conditions  which  we  can  never  hope  to 
see,  but  it  is  evident  that  all  minerals,  except  meteor- 
ites, now  upon  the  surface  of  the  globe,  in  whatever 
condition,  must  have  been  derived  either  from  it  or 
from  rocks  which  have  been  ejected  through  it.  At 
the  moment  these  began  to  decay  we  have  the  com- 
mencement of  the  whole  stratified  series,  through 


THE  FILLING  OF  MINERAL   VEINS.  119 

which,  in  some  form  or  other,  all  the  mineral  constit- 
uents of  the  original  rock  must  be  scattered,  accord- 
ing to  the  size  of  the  particles,  except  those  which 
were  perfectly  soluble;  but  always  on  lines  descend- 
ing seawards.  In  the  course  of  time  these  sediments 
would  be  again  brought  to  the  surface,  to  be  again 
worn  away  into  new  sediments,  mixed  with  the  debris 
of  a  new  series  of  eruptive  rocks,  the  process  being 
repeated  with  ever-increasing  complexity,  but  with  a 
constant  increase  in  the  metallic  contents  of  the  crust, 
if  such  were  brought  from  below  by  the  eruptive  rocks 
from  time  to  time. 

But  just  as  soon  as  fracturing  began,  and  with  it 
the  circulation  of  heated  waters,  the  concentration  of 
the  minute  particles  into  veins  would  begin,  which  as 
they  in  turn  were  eroded  would  furnish  particles  of 
larger  size  to  the  sediments,  and  in  time  these  might 
contain  sufficient  mineral  to  form  large  deposits  when 
concentrated  by  the  circulating  waters,  even  at  long 
distances  from  the  seat  of  the  original  eruptive  rocks 
from  which  the  mineral  was  derived.  Such  sediments, 
still  retaining  the  mineral  fragments,  like  the  lead 
and  copper-bearing  shales  and  sandstones,  can  be  con- 
ceived to  be  still  forming. 

We  can  now  see  why  all  fractured  regions  are  not 
metalliferous.  There  must  have  been  an  .original  area 
of  eruptive  or  volcanic  rocks  to  start  the  metal-bearing 
series,  for  without  this  no  amount  of  folding  or  dislo- 
cation could  have  produced  an  ore  vein. 

We  can  also  understand  the  spotted  or  pockety 
character  of  many  veins;  and  why  there  should  so 
often  be  in  a  district  one  strong  "mother"  vein,  as 
the  main  fissure  would  offer  more  unimpeded  channels 
for  the  circulation  of  water  than  the  smaller  lateral 
crevices;  and  why  veins  of  different  geologic  age  in 
the  same  district  should  be  filled  with  different  min- 
erals, as  the  source  from  which  the  first  series  was 
filled  may  have  been  exhausted  before  the  formation  of 
the  next. 


CHAPTER  VII. 
INFLUENCE  OF  ROCKS  ON  VEIN  FILLING. 

IT  is  evident  that  if  there  is  any  relationship  be- 
tween ore  minerals  and  rocks,  or  if,  in  other  words, 
the  useful  minerals  are  more  particularly  found  asso- 
ciated with  some  particular  rock  in  preference  to 
others,  the  knowledge  of  the  facts  would  be  of  great 
value  to  the  prospector,  for  when  he  had  gained  an 
idea  of  the  rocks  of  any  particular  district  he  would 
have  a  general  idea  of  the  minerals  which  he  was 
likely  to  find  there,  and  could  familiarize  himself  with 
their  appearance,  from  books  or  otherwise,  and 
not  only  know  what  to  look  for,  but  how  and  to  recog- 
nize them  when  found. 

The  following  imperfect  table,  compiled  from  recog- 
nized authorities,  while  far  from  being  as  complete  as 
could  be  wished  for,  undeniably  shows  that  there  is 
such  an  association  of  minerals  with  certain  rocks,  the 
reasons  for  which  we  may  not  at  present  thoroughly 
understand,  but  which  is  not  only  of  interest  but  of 
practical  importance. 

The  greatest  difficulty  in  preparing  such  a  list  is  to 
give  equal  prominence  to  all  parts  of  the  subject,  be- 
cause while  a  certain  ore  maybe  found  at  two  separate 
localities  in  two  different  rocks,  it  may  be  of  no 
especial  value  in  one  of  them  and  of  vast  importance 
in  the  other.  It  is  almost  impossible  to  correlate  such 
differences.  One  might  quote  20  mines  in  a  single 
district,  all  having  practically  the  same  character, 
and  only  one  in  another  district  of  different  rock 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.    12 1 

structure  but  producing  the  same  metal,  thus  giving 
undue  prominence  to  the  former  mode  of  occurrence; 
and  it  is  not  always  possible  to  estimate  the  "personal 
equation"  in  the  various  published  accounts,  which 
phrase  is  understood  to  include  the  amount  of  knowl- 
edge and  accuracy  of  the  writer  and  preconceived 
theories  unconsciously  coloring  his  views. 

To  overcome  these  difficulties,  and  yet  keep  the 
table  within  reasonable  limits,  a  limited  selection  of 
cases  where  the  information  was  full  enough  has  been 
made  from  the  literature  of  the  subject.  The  selec- 
tions are  for  districts,  not  individual  mines,  and  though 
insufficient  for  a  thorough  scientific  discussion,  will 
be  sufficient  for  our  purpose.  It  does  not  include  iron 
ore,  as  that  is  chiefly  found  in  bedded  deposits,  not 
subject  to  the  same  influences;  nor  the  minor  minerals, 
such  as  nickel,  cobalt,  antimony,  bismuth,  etc.,  as 
they  are  usually  the  accompaniments  of  other  ores, 
and  do  not  form  the  prominent  or  controlling  mineral 
of  the  deposit  which  imparts  to  it  its  positive  char- 
acter, although  these  may  have  a  preference  for  one 
mineral  rather  than  another,  and  occur  most  frequently 
in  combination  with  it. 


122        PROSPECTING  AND  VALUING  MINES. 


Remarks. 

111 
i    1 

g      •    Jg'tf            o 

*  ;<ti  i 

i    i  a  rf     ! 

&  jtrf  ii   *i 

>       -s^S°g          -2^ 
§       g-g-S     ^^          2-g 
•s      fa*  ^^         So 

^>         >     ^     QQ             O 

Black  clay  slates. 

Talc  and  serpentine. 
Talc  and  serpentine. 
Quartzose  and  talcose  schists 
Chloritic,  talcose  and  clay 

schists. 
Mica,  talc,  hornblende  and 
chlorite  schists. 
Mica  and  chlorite  schists. 
Mica  schists  and  in  sheeted 
walls. 

Quartzose  schists—  no  erup- 
tive rocks. 
Between  laminae. 
Schists  broken  through  by 
cVorite  dikes. 

i 

I 

i 

:  i^-d 

B"    'SS  « 

£              :  : 

:  -o  § 

9-,§  3 

^              :  : 

Nagyag,  Transylvania  .  .  . 
Sudbury,  Ontario  
Allison  mine,  Amador  Co. 
Thames  district,  New  Zea 

Telluride  belt,  Colo  
Butte  Co.,  Cal.  
Berezovsk,  Russia  
Boulder  Co.,  Colo  
'ides  WyonVg  mine.  Nevada  Co 
Soaprot  mine  CalaveraCo 
Sent"nlmine,BoulderCo., 
»s  Wermouth  concesXHonc 

.  ..0  Keystone  mine,  Amador 
Cal. 
Siberia  
Mariposa  Co.  ,  Cal  
Peshaston  Creek,  Wash.  . 
e,  galena  Yavapai  Co.,  Ariz  
Berezovsk,  Russia  

i 

1 

c 
a 
C 

Tomoh,  Siamese  Malay  'nS 
Maryland  

5 

0 

C 

Tolema,  South  America. 
Calaveras  Co.,  Cal  

Principal  and  Asso 
Minerals. 

9  •  •  •  • 
&  \\-\\ 

I  !  :  i 

M  Hi  ;  :i 

•••"•:«:  :« 

.o.o..o.  Ironpyrite  

Ironpyrite  
Ironpyrite  
Iron  pyrite,zincblend 

i 
1 

I 

•> 
\          \ 

e  rocks  

1 

II  P  tf 

1 

Trachyte  
Diorite  
Diorite  —  
Andesite..,  

Porphyry..  
Porphyry;  
Porphyry...  
Porphyry—  granite 
Granite  or  gneiss.  . 
Granite  or  gneiss.  . 
Granite  or  gneiss.  . 
Granite—  line  conta 

Slates....  

'   02   03  CO  « 

05  4-S  4J  -1-3  4^ 

cp  to  co  02  a 

02          CO   CO 

.23     .23  22 
2    22 

t>      o  o 

O2      CC02 

Schisms.  .  .  .  o  .  .  «  

Schists  
Schists  and  eruptiv 

INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.   123 


ks. 


-S  -S 


a 


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124        PROSPECTING  AND  VALUING  MINES- 


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manganese. 


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INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.    125 


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126        PROSPECTING  AND  VALUING  MINES. 


Remarks. 

+j 

1 
§ 

Q 

Vlica  slates. 
Jlay  slates. 

Associated  eruptive  rocks. 
Mica  schists  and  gneiss, 
traversed  by  granulite 
dikes  and  capped  with  ba- 
salt. Lodes  cut  the  dikes. 

1 

a 

I 

c3 

s 

s"' 

0" 

r^ 

Conglomerate  foot  wall, 
n  ash  beds  of  amvedalordal 

diabase, 
n  "trap.11 
n  "trap.11 
Denticular  beds  in  diorite. 
[n  fissured  zones  rhyolite 

near, 
n  beds, 
^eins  in  gneiss  and  quartzite. 
Sfear  contact  of  graywacke 
and  diorite,  or  in  the  dio- 
rite. 
Various  schists  associated 

; 

a 

3 

*     ' 

4* 

02 

1? 

Tombstone,  Ariz. 
Salt  Lake,  Utah.. 

Maine  
Connecticut  
Bohemia  
Cornwall  
Monte  Cristo,  Wa 
Pontgiband,  Fran 

j 

03  3             .£ 

0^3            t- 

11 

S  -     a 

'.2 

;| 

'-3  t£g 
gOttM 

Fahlun,  Sweden.. 
Maine  
Sudbury,  Ontario 

Canelton.  Quebec 

^ 

:  :  :  :& 

1 

W   CO 

i    :: 

%  :  :  :§ 

> 

33                     fV> 

Principal  and  ^ 
Minera 

LEAD-SlL 

.  Silver,  gold  
Silver  

.  Zincblende  and  cc 

.  Silver,  zincblende 
.  Silver  

.  Ziucblende  and  si 

.  Silver,  zincblend 
pyrite. 

COPPEI 

.  Native  .  . 

09 

C 

ii 

02    33 

ii 

11 

Jb 

:  :  :S 

1 

C  i^ 

sa 

"c3 

0              & 

fill 

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ii 

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O  D  33  ^3 

^.S:  ^  s 

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"fcib 

I 

-2           £ 

60                £ 
§                1 

^    aaaa 

"3  '3  ft       g 
S  ^  2       E 
cow      K 

INFLUENCE  OF  HOCKS  ON  VEIN  FILLING. 


1 

n  or  near  to  the  Carbonifer- 
ous limestone.  Another 

S    S 

ft     c 

3  I 

|co      £ 

"3    'z 

*5 

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IS 

gil 

i  i«  w  p 

i  ^  in  n  ii 

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s    •g.3l£ll|:0     M   •VF 

|  |«3Sg  .5|   §<^-sJ£ 

>!  |1s|l|ii  £jiii 

:S  laStSrii  ••Sifll 

>!§   J'S^fi-a-'SS   •SgSSS 

)         QPQ         I^M             PQcC 

Small  veins, 
n  granitic  gneiss, 
n  lime  at  contact  of  dikes 
cutting  lime  and  granite, 
ncluding  dolomites, 
ncluding  dolomites, 
ncluding  dolomites. 

i 

tjj 

Is 

il 

oo 

i 
1 

4 
1 

S 

>>                             :.S           T 

§              ^      I 

.H5J5                    "§'§1          1 

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1     dj"*          w.s§       *    a          ^ 

2     5  «  o         S  3         o^  o" 
5     OS55        HP3        OJO            C 

....  Maryland  
....  Ammerberg,  Sweden  
....  Southwest  N.  Mex  

....  England  and  Belgium  
Connecticut  
....  Wis.,  Mo.,  Iowa  and  Ills... 

Associate 
Is. 

^  cs 

T3  *-< 

ll 

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w     •  •'. 

§H    :  : 

o    w  co 
rl    9  P 

:     :  :  :        :  :       S  :  8           : 

CO     •     «                                     P<    •  fcn 

£  :fe                  ££° 

d    : 

a  Ih  Ml 

•f 
1 

( 

—  Oxidized  or 
o  .  .  .  Oxidized  01 

S=S                 8^3 

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81:        :  :        i  :  :          : 

:  :a      :  :  • 
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Granite—  lime 
Limestones  .  . 

Limestones  .  . 

w  :  :        :  :        :-g-g 

:^3coco           coco           wSS 
CCDO)              CDCD             <I>5353 

^oo         oo         oSS 

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Jit    111 

§s£  .§.§.§ 

OOPn     JJJ 

128        PROSPECTING  AND  VALUING  MINES. 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING,    129 


il 

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130 


PROSPECTING  AND  VALUING  MINES. 


In  the  following  table  the  eruptive  rocks  have  been 
necessarily  placed  together,  because  while  trachyte 
has  4  mentions,  diorite  6,  andesite  5,  rhyolite  7  and 
basalt  5,  there  are  25  notices  of  simply  igneous  rocks 
— prophyry,  trap,  or  other  indefinite  names,  which 
cannot  be  classified. 

CONDENSED  TABLE  OF  ROCKS  AND  ASSOCIATED  METALS. 


Metals, 

Eruptive  and  Intrusive. 

Sedimentary. 

Alone. 

Associated  with 

Alone. 

Contacts. 

1  Granite,  Gneiss. 
Syenite. 

Eruptive. 

Gneiss,  Granite, 
Syenite. 

Sandstone, 
Quartzite. 

Schists. 

Shales. 

Limestone. 

Sandstone, 
Quartzite 

a 

X 

Shales. 

Conglomerates. 

Limestones. 

Serpentines. 

Lime  and 
Shales. 

Lime  and 
Quartzite. 

j  Slates  and 
M  1  Sandstones. 

Gold  

7 

1 
1 

2 

5 

1 

1 

1 

(.) 

1 

2 

1 

Silver  

2 

s 

5 

2 

i 

1 

1 

2 
5 

3 

1 

1 

Lead  

2 

4 
1 

*2 
2 

4 
2 
f> 

1 

3 
1 

.... 

3 
q 

4 

8 

5 

Zinc 

1 

Tin  

5 

1 

2 

7 

1 

2 

6 

tl 

By  further  condensation  we  have  the  following  table : 

COUNTRY  ROCKS  BROADLY  GROUPED. 


Metals. 

Granite,  Gneiss, 
and  Syenite. 

Sedimentary 
Rocks. 

Associated  with 
Eruptive  Rocks. 

Totals. 

Gold.  

3 

15 

16 

34 

Gold  and  silver.. 

1 

2 

3 

Silver  

2 

5 

11 

18 

Lead  

3 

16 

0 

25 

Copper  

3 

11 

7 

21 

Zinc  

2 

5 

1 

g 

Tin  

5 

2 

1 

$ 

Chrome  

7 

7 

Manganese  

1 

2 

2 

Mercury  

4 

6 

10 

19 

68 

50 

137 

*  Probably  remains  of  beds  of  lime,    i  All  in  belts  of  hot  springs. 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.     131 

The  rocks  in  the  foregoing  tables  may  be  further 
classified  according  to  the  amount  of  silica  or  quartz 
which  they  contain,  into  three  groups: 

\.  Highly  silicious:  Granite,  gneiss,  mica  schists, 
sandstones,  conglomerates,  quartzites,  eruptive  rocks, 
and  some  limestones. 

'2.  Moderately  silicious:  Chlorite,  talc  and  clay  schists 
and  shales,  conglomerates  in  part,  and  some  lime- 
stones. 

3.   Scarcely  silicious:  Limestones  and  dolomites. 

Examining  the  metals  in  the  foregoing  list  we  find 
in  the  case  of — 

Gold. — Twenty-six  occurrences  in  rocks  abounding 
in  quartz  (silica)  out  of  the  34  localities,  and  in  some 
of  the  remainder  the  same  conditions  probably  exist, 
as  many  shales  and  conglomerates  are  highly  silicious. 
Only  one  occurrence  is  noted  with  limestone  and  in 
this  case  the  foot  wall  of  the  deposit  is  granite. 

Gold  and  Silver. — All  three  occurrences  are  in  rocks 
abounding  in  silica. 

Silver  (aside  from  silver-lead  ores  which  are  classed 
as  lead)  occurs  in  13  very  quartzose  rocks  out  of  18 
instances,  and  the  remaining  5  are  probably  silicious, 
as  many  limestones  are  highly  silicious. 

Copper  also  occurs  with  18  very  quartzose  rocks, 
and  probably  with  19  out  of  the  21  localities,  if  not 
more,  as  the  Clifton  deposits  are  differently  described 
by  two  writers,  and  the  other  limestone  locality  may 
carry  much  quartz. 

Lead,  however,  occurs  in  the  quartzose  series  in 
only  10  out  of  25  localities,  the  remaining  15  being  in 
association  with  limestones,  while  some  of  the  former 
may  have  lime  to  some  extent  as  a  minor  constit- 
uent. 

Zinc  shows  6  out  of  8  times  as  an  associate  of  lime- 
stone and  only  twice  in  the  quarfczose  group. 

Tin. — All  8  of  the  occurrences  are  in  quartzose 
rocks. 


132         PROSPECTING  AND  VALUING  MINES. 

Chrome. — All  7  localities  are  in  serpentines,  usually 
associated  with  gneissic  or  hornblendic  rocks. 

Manganese  is  associated  with  both  extremes  of  rock. 

Mercury. — All  10  localities  are  in  highly  metamor- 
phosed rocks  of  various  kinds,  but  nearly  all  are  asso- 
ciated with  recent  eruptive  rocks  and  hot  springs. 

The  relative  importance  of  these  occurrences  is  best 
tested  by  the  output  commercially  of  the  different 
metals.  Tested  in  this  way,  the  highly  silicious 
rocks  produce  the  bulk  of  the  gold,  silver,  copper  and 
tin ;  the  non-silicious  or  true  limestone  rocks,  the 
bulk  of  the  lead  and  zinc,  and  rocks  which  on  decom- 
position yield  both  silica  and  lime,  give  complex  ores 
of  gold,  silver,  lead,  copper,  zinc,  tin  and  manganese, 
with  many  other  less  prominent  metals. 

Metals  Associated  With  Each  Other. — Gold  and 
silver  are  so  intimately  associated  in  nature  that  all 
gold  may  be  said  to  contain  some  silver;  and  most 
silver  ores  carry  gold,  from  mere  traces  up  to  impor- 
tant values.  Gold  containing  a  large  proportion  of 
silver  is  pale  in  color  and  is  sometimes  called  "elec- 
trum  ;"  while  some  native  gold-silver  alloys  are  almost 
white. 

Lead  and  silver  are  also  so  related  that  lead  ores  as  a 
rule  carry  some  silver,  if  only  a  trace,  and  from  that 
up  to  large  amounts  in  value,  though  not  in  bulk, 
without  any  special  change  in  their  outward  appear- 
ance. 

Lead  and  zinc  are  also  intimate  associates,  as  are 
also  lead  and  antimony. 

Copper  and  silver,  or  copper,  silver  and  gold,  often 
go  together. 

Iron  and  manganese,  or  iron  and  chrome,  are  fre- 
quently associated. 

Nickel  and  cobalt  are  closely  related,  both  chemi- 
cally and  in  occurrence. 

Arsenides  and  antimonides  of  other  metals  are 
often  found  together,  and  either  or  both  with  sul- 
phides. 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.     133 

Country  Rock  and  Gangue. — The  ore  minerals  proper 
usually  compose  only  a  fraction  of  the  whole 
vein  filling,  the  gaiigue  minerals  being  present  in 
larger,  often  very  much  larger  quantity.  The  rocks 
through  which  the  underground  waters  pass  must  con- 
tain material  suitable  to  form  this  gangue — silica  for 
the  quartz,  lime  for  the  calcite,  fluorine  for  fluorspar, 
sulphur  for  the  sulphate  minerals,  etc.  The  gangue 
minerals  are  closely  related  to  the  metals  and  true  ore 
minerals  (as  quartz  to  gold,  calcite  to  galena,  etc.); 
hence  the  connection  is  really  threefold — country  rock, 
gangue,  ore. 

Relation  of  Eruptives. — While  eruptive  rocks  are 
frequent  accompaniments  of  ore,  they  are  not  abso- 
lutely essential  to  its  presence  either  in  the  silicious 
rocks  of  Otago,  New  Zealand ;  or  the  sandstone  reefs 
of  Bendigo,  Australia,  or  the  non-silicious  limestones 
of  the  Central  States  in  America.  In  only  50  out  of 
137  cases  are  eruptive  rocks  mentioned  in  connection 
with  the  ore  deposits  as  being  of  possibly  prior  origin, 
or  about  36%,  while  in  68  cases,  or  about  50%,  there 
is  no  apparent  connection  of  either  eruptive  rocks  or 
granite.  Possibly  eruptives  existing  in  the  neighbor- 
hood of  ore  deposits,  but  not  actually  contiguous,  are 
sometimes  overlooked  or  not  reported. 

There  are  cases  in  which  the  metal  in  the  deposits 
undoubtedly  appears  to  have  been  derived  from  them. 
But  outside  of  these  instances  there  are  others  where 
the  outbursts  of  eruptive  rocks  have  simply  produced 
the  necessary  conditions  of  heat  and  fractured  rocks, 
furnishing  waters  of  the  requisite  temperature  and  pro- 
viding ample  facilities  for  their  percolation  through 
materials  so  crushed  as  to  be  easily  soluble. 

Similar  results  have  been  obtained  in  other  places, 
without  the  aid  of  eruptive  rocks,  by  the  enormous 
pressure  involved  in  the  complicated  folding  which  we 
see  in  such  cases  as  the  sandstone  reef  at  Bendigo, 
Australia,  or  the  abruptly  folded  strata  in  Nova  Scotia, 


134         PROSPECTING  AND  VALUING  MINES. 

so  that  it  would  appear  that  any  cause  which  will  pro- 
duce heated  water  and  fractured  rocks  is  sufficient  to 
furnish  the  conditions  for  vein  filling,  the  material  for 
forming  the  deposit  being  drawn  from  any  one  or  all 
of  the  rocks  indiscriminately  through  which  the  water 
has  been  circulating,  whether  above,  below,  or  along- 
side, near  to  or  at  considerable  distances  from  the 
point  of  final  deposit;  and  that  this  place  of  final 
deposit  is  largely  determined  by  the  character  of  the 
rock  through  which  the  water  may  be  circulating  at 
the  time  it  is  compelled  to  part  with  some  portion  of 
its  mineral  burden,  and  not  by  the  character  of  the 
cause  which  produced  the  fissures,  or  the  nature  of  the 
associated  eruptive  rock,  unless  the  ore  is  deposited 
in  thi  t  rock  itself.  The  following  extracts  strike  the 
keynote  and  indicate  a  line  of  examination  which  will 
explain  nearly  all,  if  not  quite  all,  the  phenomena  of 
the  association  of  minerals  with  each  other,  and  the 
rocks  in  which  they  occur.  Speaking  of  the  ore  de- 
posits in  the  Potsdam  series  of  rocks  in  South  Dakota, 
Dr.  F.  B.  Carpenter  says:  "These  ores  are  in  some 
sections,  almost  exclusively  gold-bearing;  in  others, 
they  carry  partly  gold  and  partly  silver,  and  again  in 
other  places  the  silver  predominates."  "It  seems  as 
though  the  porphyry  at  Bald  mountain  brought 
mainly  gold ;  at  Buby  basin,  only  a  few  miles  distant, 
gold  and  silver  in  nearly  equal  quantities  (in  value); 
while  at  Galena,  12  miles  distant,  silver-lead  predomi- 
nated. That  is,  broadly  speaking,  gold  predominates 
in  the  quartzites,  but  gives  place  to  silver  as  we  ap- 
proach the  more  calcareous  portions  forming  the  upper 
parts  of  the  Potsdam;  while  in  the  massive  limestones 
such  ore  bodies  as  are  found,  like  the  Iron  Hill,  carry 
exclusively  lead  and  silver,  yet  the  porphyry  is  in  all 
instances  the  same." 

Variations  in  the  Mineral  Solutions. — But  in  following 
up  this  line  of  argument  we  must  remember  that 
all  waters  will  not  be  charged  with  the  same  mineral, 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.     135 

or  the  same  water  always  with  the  same  mineral,  as 
their  contents  must  vary  with  the  nature  of  the  rocks 
from  which  they  draw  their  supply,  and  consequently 
they  can  only  deposit  what  they  have  in  solution  for 
the  time  being,  and  may  carry  that  for  long  distances 
for  want  of  a  suitable  precipitating  agent.  They  may 
have  only  one  or  many  minerals  in  solution,  but  at  any 
rate  we  are  prepared  to  understand  the  occurrence  of 
gold  in  the  joints  of  porphyry,  of  silver  in  the  joints 
of  quartzite,  of  lead  and  silver  in  the  seams  of  lime- 
stone, and  why  the  character  of  the  ore  should  change 
so  suddenly  when  a  vein  passes  from  one  series  of 
rocks  to  another,  as  for  instance  from  a  silver-bearing 
galena  with  zincblende  and  iron  pyrite  in  decaying 
porphyries  with  lime  feldspars,  or  a  gold-bearing 
arsenical  pyrite  in  the  underlying  granite;  from 
copper  in  silicious  slates  to  tin  in  a  still  more  silicious 
granite,  where  also  the  character  of  the  mica  (white 
mica  being  common  in  tin-bearing  rocks)  appears  to 
have  an  influence,  or  to  be,  like  tin,  a  result  of  the  same 
influence;  or  from  deposits  of  galena  in  limestone  to 
barren  material  in  the  intercalated  beds  of  " toad- 
stone"  (an  ancient  eruptive  rock),  as  in  the  lead 
deposits  of  Derbyshire,  England. 

Influence  of  the  Country  Eocks. — The  practical 
miner,  however,  is  not  so  much  interested  in  the 
scientific  explanation  of  such  sudden  changes,  but  he 
is  very  materially  interested  in  the  fact  that  they  do 
occur,  as  they  may  involve  serious  and  costly  changes 
in  the  character  of  the  reduction  plant,  or  a  loss  of  the 
vein  altogether,  as  at  the  Stonewall  Jackson  mine, 
Arizona,  where  the  native  silver  found  in  the  surface 
porph3rry  disappeared  altogether  when  the  underlying 
granite  was  reached;  or,  as  on  the  Comstock  lode, 
when  the  fissure  left  the  syenite-porphyry  contact  and 
passed  into  the  underlying  syenite,  where  it  presented 
only  occasional  bunches  of  gold  ore,  instead  of  the 
silver  deposits  of  the  eruptive  contact  levels. 


136         PROSPECTING  AND  VALUING  MINES. 

The  lesson  inculcated  is  the  desirability,  to  say  the 
least,  of  a  thorough  examination  of  the  line  of  outcrop 
of  the  deposit  under  consideration,  before  erecting 
reduction  works,  not  only  to  avoid  the  necessity  of 
change,  but  to  determine  the  probable  extent  of  the 
ore-bearing  ground  ;  for  if  the  ore  be  confined  to  a  cer- 
tain class  of  rocks  in  any  particular  district,  the 
extent  to  which  such  rocks  are  developed  is  an  impor- 
tant element  in  the  future  of  a  mining  camp,  and  must 
largely  govern  the  amount  of  money  which  it  will  be 
wise  to  invest  in  means  of  transportation,  etc. 

The  views  here  set  forth  also  explain  why  long  belts 
of  country  produce  similar  ores,  while  parallel  belts  at 
no  great  distance — often  only  a  few  miles — may  pro- 
duce a  totally  different  series  over  a  like  extent  of 
country ;  or  why  the  ores  on  one  side  of  a  mountain 
range  should  present  a  totally  different  appearance 
from  those  on  the  other,  where  both  series  have  been 
subjected  to  the  action  of  the  same  eruptive  rocks,  or 
to  no  such  action  on  either  side.  It  is  simply  because 
they  occur  in  parallel  belts  of  rock  of  differing  com- 
position, the  outcrops  of  which  are  presented  to  us  on 
the  flanks  of  the  mountain  ranges  in  which  they  lie, 
more  or  less  parallel  to  the  general  summit  of  the 
range  or  axis  of  elevation.  Thus  below  the  free  gold 
belt  of  the  mother  lode  in  California — which,  however, 
is  not  a  lode  in  the  true  sense  of  the  word,  but  a  belt 
of  gold-bearing  rocks,  in  which  many  deposits  occur 
roughly  parallel  to  the  general  strike — there  lies  in  the 
foot  hills  a  band  of  copper-bearing  rocks  of  equal  extent 
north  and  south,  while  higher  up  in  the  range  there  is 
a  belt  of  limestone  country  with  which  are  associated 
ores  of  a  more  complex  character,  galena  as  might  have 
been  expected  making  its  appearance. 

Again,  just  as  the  ancient  schists  of  the  Carolinas 
and  Georgia  furnish  ores  of  the  same  character,  over  a 
distance  of  many  miles,  so  do  the  ancient  metamor- 
phosed rocks  of  the  Cascade  range,  in  Washington,  fur- 


INFLUENCE  OF  ROCKS  ON  VEIN  FILLING.    137 

nish  for  miles  on  the  western  slope  complex  ores  of 
very  uniform  character  in  each  member  of  the  rock 
series,  but  differing  entirely  from  those  on  the  eastern 
flank  of  the  same  range. 

It  is  for  such  reasons  as  these  that  geological  surveys 
may  be  of  very  great  utility,  if  they  can  be  made  be- 
fore the  districts  have  been  exhausted  and  all  the 
thousand  and  one  experiments  and  failures  have  been 
tried  and  made;  but  of  no  direct  and  local  value  what- 
ever if  undertaken  when  the  mining  camp  is  wellnigh 
deserted,  although  perhaps  useful  in  showing  a  com- 
parison with  other  localities. 


CHAPTER  VIII. 
MINERAL  DEPOSITS  OTHER  THAN  VEINS, 

Succession  of  Formations. — -As  we  have  seen  in  dis- 
cussing the  filling  of  veins,  it  was  not  necessary  in 
their  case  that  the  filling  should  have  been  derived 
from  rocks  which  lay  at  a  greater  altitude  than  the 
deposits  which  were  being  formed,  although  without 
doubt  a  large  portion  of  them  may  have  been  so  situ- 
ated, but  in  the  formation  of  bedded  deposits  in  strat- 
ified rocks  only  a  very  insignificent  portion  are 
derived  from  springs,  thermal  or  otherwise.  Deposits 
are  laid  down  on  the  top  of  rocks  already  formed  and 
covered  up  by  others  of  a  later  date.  While  these 
latter  must  of  necessity  lie  conformably  on  the  deposit, 
or  cover  it  horizontally,  those  on  which  the  deposit 
lies  were  not  necessarily  so.  A  mineral  formation 
may  follow  in  orderly  succession  as  one  of  numerous 
layers,  or  it  may  be  laid  down  on  the  upturned  edges 
of  older  strata,  which  have  been  tilted  up  and  largely 
worn  away  before  they  sank  again  beneath  the  water 
and  received  a  new  covering.  In  pi.  2,  fig.  1,  the 
strata  E,  G,  D,  lie  conformably  on  each  other,  but  un- 
conformably  on  the  tilted  series  A.  If  there  be  also 
such  a  series  as  B  we  infer  that  it  was  laid  down  on  A\ 
that  a  gradual  horizontal  upraise  brought  B  out  of 
the  water  and  permitted  the  destruction  of  most  of  the 
series;  and  that  a  subsequent  depression,  without  tilt- 
ing, allowed  the  deposition  of  E,  C,  D,  which  are  also 
said  to  be  unconformable  to  B;  but  it  is  evident  that 
it  will  be  much  more  difficult  to  trace  the  true  rela- 


MINERAL  DEPOSITS  OTHER  THAN  VEINS.     139 

tionship  between  E.C.D  and  B  than  between  #and  A, 
or  between  E,  C,  D  and  A. 

The  most  important  deposits  to  us,  outside  of  clays 
and  those  which  have  formed  building  stones,  are 
those  of  coal  and  iron  ore;  salt,  gypsum,  carbonate  of 
soda,  niter,  and  the  allied  minerals.  The  action  of 
water  is  evident  in  the  formation  of  all  these,  as  the 
agent  by  which  the  material  has  been  collected,  except 
in  the  case  of  coal,  whether  they  have  been  made  by 
the  ocean,  to  which  the  contained  minerals  have  been 
carried  by  streams  from  higher  altitudes,  or  in  inland 
basins  long  since  dried  up,  to  the  lower  portions  of 
which  other  rivers  have  carried  in  solution  the  mate- 
rials derived  from  the  ridges  bounding  the  basin,  and 
which  are  now  in  process  of  decay. 

Solvent  Capacity  of  Water,  and  Evaporation. — We 
have  seen  previously  that  heated  waters  have  the  power 
of  holding  in  solution  a  larger  quantity  of  any  given 
material  than  those  of  lower  temperatures,  and  that  in 
cooling  they  are  compelled  to  deposit  a  portion  of  their 
load,  as  in  the  case  of  hot  springs,  wrhich  build  up 
masses  of  sinter  around  their  orifices.  The  quantity  of 
mineral  matter  which  such  springs  may  bring  to  the 
surface  will  be  better  understood  by  the  statement  of 
Prof.  Kamsay  that  the  hot  springs  at  Bath,  England, 
discharge  annually  sufficient  solid  matter  to  make  a 
column  140  ft.  high  by  9  ft.  in  diameter.  But  whether 
hot  or  cold  there  is  in  any  case  a  point  at  which  waters 
have  absorbed  and  hold  in  suspension  the  maximum 
quantity  possible.  This  is  called  the  saturation  point, 
and  such  a  solution  is  said  to  be  saturated.  If  more 
solid  matter  is  added  to  such  a  solution  it  falls  to  the 
bottom  undissolved,  or  if  the  amount  of  water  be  re- 
duced by  evaporation  the  same  result  follows;  a  por- 
tion of  the  dissolved  matter  is  squeezed  out  of  the 
solution  as  its  particles  contract  on  each  other,  and 
falls  to  the  bottom.  The  incrustation  on  boilers  is 
the  result  of  just  such  a  process,  and  the  principle  is 


140         PROSPECTING  AND  VAL  UING  MINES. 

applied  artificially  in  the  production  of  salt  from  brine. 
In  nature  we  see  it  in  the  drying  of  the  ground  after 
rain  by  the  winds  and  sunshine,  the  ground  losing 
and  the  air  absorbing  the  moisture;  but  few  persons 
realize  that  the  loss  from  large  reservoirs  is  equal  to 
36  in.  annually  over  the  entire  surface;  and  is  still 
greater  in  shallow  waters,  where,  in  excessively  hot 
and  dry  climates,  the  loss  by  evaporation  may  rise  to 
as  much  as  1  in.  in  24  hours,  still  going  on  even  dur- 
ing the  night.  So  great  indeed  is  this  evaporation  in 
the  deserts  of  the  Great  American  basin  that  all  the 
rainfall  is  taken  up  in  this  manner,  the  numerous 
lakes  having  no  outlet,  but  varying  in  size  from  month 
to  month,  and  day  to  day,  as  the  rainfall  or  sunshine 
gains  the  mastery,  shrinking  in  hot  and  dsy  and  ex- 
panding in  cool  or  wet  weather,  and  always  maintain- 
ing an  area  which  is  just  large  enough  to  enable  the 
evaporating  agencies  to  take  up  the  exact  amount  of 
•water  flowing  into  the  lakes.  The  popular  notion  of 
subterranean  outlets  for  this  water  has  no  foundation 
in  fact,  as  evaporation  is  sufficient  to  account  for  all 
the  phenomena. 

But  in  this  process  it  is  only  the  water  which  is  lost; 
whatever  minerals  or  solid  matter  it  brought  down 
from  the  mountains  into  the  lakes  is  left  there,  accu- 
mulating slowly  but  surely,  no  matter  how  small  the 
amount  may  be  per  gallon  of  water,  until  sooner  or 
later  the  saturation  point  is  reached,  and  a  deposit 
begins  to  form  of  whatever  salt  may  be  least  easily 
held  in  solution,  if  there  be  more  than  one.  For  a 
time  the  annual  influx  of  water  may  be  able  to  redis- 
solve  the  precipitated  portion,  during  the  more  rainy 
part  of  the  year,  but  in  the  course  of  time  this  precipi- 
tate will  exceed  in  quantity  the  amount  soluble  in  the 
annual  inflowing  water  and  a  permanent  deposit  will 
begin,  the  surface  of  which  will  suffer  a  partial  re- 
solution annually,  but  the  mass  itself  steadily  increas- 
ing in  bulk.  In  this  inauner  have  gypsum,  rock  salt 


MINERAL  DEPOSITS  OTHER  THAN  VEIES.     141 

and  carbonate  of  soda  been  deposited  from  saline 
waters;  gypsum  from  sea  water,  saturated  with  the 
sulphate  of  lime,  but  able  to  hold  all  its  chloride  of 
sodium  (common  salt)  in  solution ;  salt  from  similar 
waters  by  evaporation,  the  salt  in  such  cases  contain- 
ing the  small  amounts  of  sulphate  of  lime  and  other 
minerals  which  may  be  in  solution  and  which  consti- 
tute its  impurities.  Both  of  these  substances  are 
therefore  purely  mechanical  precipitates.  Natural 
evaporation  has  in  this  way  produced  enormous 
masses  of  rock  salt,  like  those  of  Cheshire,  England, 
and  Cracow  in  Poland,  both  of  which  are  extensively 
opened  by  underground  works;  or  that  at  Sperenberg, 
near  Berlin,  which  has  been  penetrated  by  an  artesian 
boring  to  a  depth  of  3,907  ft.  without  the  bottom  hav- 
ing been  discovered ;  or  those  which  are  exposed  on 
the  surface  on  the  Bio  Yirgen  (or  Virgin  Biver)  in 
Nevada,  which  are  described  as  follows:  "A  formation 
exists  at  this  point  composed  of  rock  salt  resting  on, 
and  to  some  extent  intermixed  with,  sedimentary 
rocks,  and  of  such  magnitude  that  it  may  be  said  to 
constitute  a  notable  portion  of  the  hill  in  which  it 
occurs.  More  than  60%  of  this  entire  mass  appears 
to  consist  of  hard  rock  salt,  having  the  transparency 
of  clear  ice,  and  containing  over  90%  sodium  chloride. 
This  formation  extends  along  the  eastern  bank  of  the 
Yirgen,  presenting  a  bluff  face  to  the  stream  for  a  dis- 
tance of  25  miles  or  more,  and  reaching  in  some  places 
a  height  of  several  hundred  feet. " 

These  deposits  are  so  enormous  that  we  might  even 
be  disposed  to  question  the  power  of  so  simple  a  cause 
to  accomplish  the  results  which  are  still,  however, 
being  reached  at  Carmen  island  in  the  Gulf  of  Cali- 
fornia and  elsewhere,  but  the  following  description  of 
the  Karaboghaz  sea  (from  Sir  A.  Geikie)  will  show 
them  to  be  not  only  probable  but  possible:  cc Along 
the  shallow  pools  which  border  this  sea  (the  Caspian) 
a  constant  deposition  of  salt  is  taking  place,  forming 


142         PROSPECTING  AND  VALUING  MINES. 

sometimes  a  pan  or  layer  of  rose-colored  crystals  on 
the  bottom,  or  gradually  getting  dry  and  covered  with 
drift  sand.  This  concentration  of  the  water  is  still 
more  marked  in  the  great  offshoot  called  the  Kara- 
boghaz,  which  is  connected  with  the  middle  basin  by 
a  channel  150  yds.  wide  and  5  ft.  deep.  Through 
this  narrow  mouth  there  flows  from  the  main  sea  a 
constant  current,  which  Yon  Baer  estimated  to  carry 
daily  into  the  Karaboghaz  350,000  tons  of  salt." 

This  amount  if  all  deposited  would  cover  250  acres 
to  a  depth  of  1  ft. 

Such  deposits  belong  not  only  to  the  open  sea,  but 
mostly  to  inland  seas  or  lakes  which  have  originally 
formed  a  portion  of  it,  and  consequently  partook  of 
the  general  diffusion  of  the  salts  which  are  discharged 
into  it  by  the  rivers  through  its  entire  bulk.  The 
deposits  which  result  from  the  concentration  of  min- 
erals in  isolated  fresh  water  lakes  will  naturally  par- 
take somewhat  more  of  the  character  of  the  salts  fur- 
nished by  the  rocks  undergoing  decomposition,  and 
which  are  gradually  water-borne  to  the  deepest  depres- 
sions or  sink  holes,  there  to  be  evaporated  and  con- 
centrated or  deposited.  To  such  causes  can  we  cer- 
tainly attribute  the  lakes  furnishing  the  carbonate 
of  soda  and  sulphate  of  soda  so  common  in  the  desert 
regions  of  Nevada,  Utah  and  Wyoming,  and  the 
salines  producing  borax,  and  the  nitrates  of  potassium 
(saltpeter)  and  of  sodium  (Chili  saltpeter)  in  the  same 
regions  and  also  in  the  deserts  of  South  America;  and 
the  bitterness  of  Mono  lake  and  other  waters  due  to 
the  presence  of  sulphate  of  magnesia  (Epsom  salt). 

With  such  an  origin  it  is  plain  that  the  efflorescence 
or  crusts  of  these  easily  soluble  salts  are  to  be  sought 
for  mainly  in  arid  regions,  where  the  rainfall  is  not 
sufficient  to  re-dissolve  them  after  formation,  and  that 
chiefly  during  the  hottest  portion  of  the  year  when 
evaporation  has  done  its  work  most  thoroughly.  The 
presence  of  these  salts  in  streams  need  not  be  per- 


MINERAL  DEPOSITS  OTHER  THAN  VEINS.     143 

ceptible  to  the  taste,  for  even  good  drinking  waters 
may  carry  an  average  of  20  grains  of  solid  matter  per 
gallon  in  solution,  but  the  constant  accumulation  of 
even  this  small  amount,  if  carried  on  for  a  time  suffi- 
ciently long,  will  produce  all  the  phenomena  we  have 
been  describing. 

Alternate  Evaporated  Deposits. — It  must  not,  how- 
ever, be  supposed  that  these  deposits  are  always  uni- 
form in  quality  throughout.  In  many  localities  they 
consist  of  alternating  beds  of  salt,  gypsum  and  clays; 
or  carbonate  of  soda,  salt,  gypsum,  Chili  saltpeter  and 
boracic  materials  with  clay  partings,  laid  down  as  one 
or  other  of  the  materials  predominated  in  the  water 
supply,  owing  to  changes  in  the  character  of  the  rocks 
from  which  the  salts  were  drawn,  and  varying  accord- 
ing to  relative  solubilities.  It  can  also  easily  be  un- 
derstood that  they  will  thin  out  in  every  direction 
round  their  boundaries,  which  are  also  apt  to  be  mixed 
with  impurities  blown  into  the  lakes  from  the  dry 
sandy  wastes,  or  forced  in  by  the  sudden  rush  of  water 
caused  by  cloudbursts. 

Sediment  Mineral  Deposits. — Besides  the  mineral 
salts  carried  in  solution  by  water,  it  is  likely  that 
some  bedded  deposits  owe  a  portion  at  least  of  their 
contents  to  particles  of  mineral  brought  in  suspension 
by  flowing  water  and  deposited,  like  other  finely 
divided  suspended  matter  which  goes  to  form  shales, 
slates,  etc.,  when  the  current  was  checked  and  no 
longer  able  to  carry  them. 

.Beds  of  Iron  Ore. — It  is  evident  that  in  all  these 
cases  there  is  not  necessarily  any  chemical  action  tak- 
ing place,  after  the  water  has  once  absorbed  the 
material  to  be  deposited,  but  such  is  not  always  the 
case  in  the  formation  of  iron  deposits. 

While  some  iron  ore  is  formed  in  lodes,  or  cavities 
in  limestone  as  a  deposit  from  ferric  waters  (waters 
carrying  iron),  probably  the  larger  bulk  of  iron 
deposits  have  heen  thrown  down  in  beds  in  the  waters 


144         PROSPECTING  AND   VALUING  MINES. 

of  swamps  or  lakes,  through  the  absorptioD  of  oxygen 
from  plants  and  diatoms  (infusoria)  accompanied  by 
the  liberation  of  hydrogen  and  carbon  in  the 
shape  of  marsh  gas.  Bog  iron  forms  in  marshy 
ground  in  such  a  manner  at  the  present  day,  out  of 
waters  which  have  become  charged  with  iron,  col- 
lected from  the  sands  and  rocks  through  which  they 
have  traveled  ;  and  where  the  accumulations  of  nodules 
and  concretions  have  been  removed,  the  formation  of 
others  shows  that  the  process  is  still  in  action.  Such 
deposits  will  naturally  be  most  impure  round  their 
margins,  as  in  the  case  of  coal  and  the  minerals  just 
under  consideration,  and  may  range  from  mere  mix- 
tures of  sand  and  iron,  or  ironstone  and  clay,  up  to 
iron  ores  of  great  purity,  according  to  the  conditions 
under  which  they  were  formed.  True,  heat  and  pres- 
sure have  modified  many  of  them,  eliminating  the 
water  from  the  brown,  and  converting  them  into  red 
hematites,  which  by  still  further  changes  may  have 
been  altered  into  magnetites. 

Many  of  these  deposits  covered  so  large  an  area  that 
now  that  they  have  been  uplifted  along  with  the  rocks 
which  contain  them,  and  have  lost  a  portion  of  one  of 
their  edges  by  erosion,  they  present  the  appearance  of 
true  contact  veins,  and  can  be  worked  as  such ;  but 
from  the  difference  of  their  origin  they  are  likely  to 
maintain  a  uniform  thickness  for  much  greater  lengths 
and  depths  than  true  veins,  and  also  to  retain  a  more 
uniform  constitution. 

Beds  of  Gold,  Copper,  Silver  and  Lead  Ores. — The 
formation  of  beds  of  conglomerates  containing  gold, 
as  in  South  Africa,  or  copper  as  in  the  Lake  Superior 
region  ;  of  sandstones  containing  copper  as  in  Europe, 
or  silver  as  at  Leeds  in  southern  Utah,  or  shales  con- 
taining galena,  has  in  nowise  differed  from  the  forma- 
tion of  similar  deposits  in  which  minerals  of  value 
have  not  been  found.  It  is  only  the  presence  of  min- 
eral in  them  which  calls  for  attention.  The  native 


MINERAL  DEPOSITS  OTHER  THAN  VEINS.     145 

copper  in  both  conglomerates,  sandstones  and  amyg- 
daloidal  traps  (or  ancient  eruptive  rocks)  of  Lake 
Superior  may  have  been  subsequently  introduced  by 
the  infiltration  of  waters  carrying  copper  in  solution, 
from  which  the  copper  was  abstracted  by  the  reducing 
and  transforming  agency  of  the  iron  in  the  rocks,  or 
in  other  cases  may  have  even  been  introduced  at  the 
time  the  beds  of  sandstone,  etc.,  were  laid  down,  and 
the  same  may  be  said  of  the  grains  of  galena  in  shales, 
but  it  must  be  confessed  that  the  true  origin  of  these 
metallic  or  metalliferous  grains  is  wrapped  in  some 
obscurity  as  regards  the  question  of  time.  The  same 
may  be  said  of  the  chloride  of  silver  associated  with 
the  vegetable  remains  in  the  sandstones  at  Leeds,  the 
difficulty  here  being  as  in  the  other  cases  to  account 
for  the  presence  of  mineral  in  one  bed  of  sandstone 
and  its  absence  from  other  similar  formations.  We 
can  only  suggest  that  in  the  Leeds  sandstone  waters 
carrying  silver  in  solution  were  compelled  by  the 
nature  of  the  stratification  to  traverse  the  band  of 
sandstone,  before  its  vegetable  remains  had  become 
petrified,  and  in  that  condition  acted  as  reducing 
agents  on  the  argentiferous  waters;  or  that  the  bed  of 
sandstone  was  formed  under  such  circumstances,  from 
rocks  containing  silver,  that  the  sediment  was  a  com- 
pound of  both  materials,  which  subsequently  under- 
went a  chemical  rearrangement  through  the  action  of 
percolating  waters,  in  which  the  organic  remains 
played  the  part  just  assigned  to  them,  just  as  organic 
matter  like  charcoal  will  precipitate  gold  from  its 
solution  in  chlorine. 

The  useful  metals  other  than  gold,  iron,  copper  and 
manganese  (which  is  also  precipitated  from  sea  water 
by  organic  remains  such  as  bones),  are,  however, 
derived  to  so  small  an  extent  from  ancient  beds  that 
their  occurrence  in  them  is  more  of  a  mineralogical 
curiosity  than  an  important  problem  for  the  miner, 
who  is  chiefly  interested  in  being  able  to  distinguish 


146         PROSPECTING  AND  VALUING  MINES. 

between  a  bed  and  a  true  vein,  on  account  of  the 
greater  certainty  of  permanence  in  the  former  and 
the  probabilities  of  its  position  underground. 

Dip  of  Mineral  Beds — As  a  bed  belongs  to  a  series 
of  strata  which  may  have  been  uplifted,  so  that  a  por- 
tion of  them  has  become  visible  on  the  surface  as 
parallel  outcrops,  there  is  no  certainty  that  the  appar- 
ent dip  of  the  strata  (that  is,  what  can  be  seen  at  any 
one  point  of  exposure)  will  be  the  permanent  dip  of 
the  entire  deposit.  The  probabilities  are  altogether 
against  such  a  supposition,  and  in  favor  of  a  flattening 
out  as  the  dip  is  followed  downward  toward  what  must 
be  the  center  of  the  basin,  of  which  we  see  portions  of 
the  rim  only  as  in  the  case  of  the  strata  seen  on  the 
left  half  of  pi.  3,  fig.  5,  or  the  right  hand  halves  of  pi. 
4,  figs.  2  and  3.  It  does  not,  however,  follow  that  all 
the  strata  exposed  will  reappear  when  the  other  edge 
of  the  basin  is  found  and  explored,  because  some  of 
them  may  have  thinned  out  and  disappeared  in  the 
intermediate  space,  and  their  place  be  occupied  by 
others,  or  the  other  edge  of  the  basin  may  not  be  seen 
on  the  surface  at  any  point,  being  covered  up  by  rocks 
belonging  to  later  epochs. 

When  strata  thus  dip  together  toward  each  other, 
forming  a  trough  or  basin,  they  are  said  to  be  "syn- 
clinal;" when  they  dip  away  from  each  other,  as  in 
the  left  hand  side  of  pi.  4,  figs.  2  and  3,  or  like  the 
two  sloping  sides  of  a  roof,  they  are  said  to  be  "anti- 
clinal;" In  the  former  case  they  may  rapidly  pass 
out  of  the  limits  of  a  surface  claim  and  enter  adjacent 
ground,  in  which  they  may  be  reached  by  shafts.  In 
the  latter  case,  they  may  pass  out  just  as  rapidly  if 
only  a  small  portion  of  the  top  of  the  anticlinal  fold 
has  disappeared  and  the  location  be  based  on  an  out- 
crop of  the  flat  top  of  the  arch  or  fold;  but  as  more  of 
the  fold  has  been  removed  the  dip  will  apparently  be 
steeper,  reaching  its  maximum  half  way  between  the 
top  of  the  fold  and  the  bottom  of  the  adjacent  trough 


MINERAL  DEPOSITS  OTHER  THAN  VEINS.    14? 

if  the  folding  be  perfectly  regular;  such,  however,  is 
scarcely  ever  the  case,  but  the  principle  involved  is 
the  same,  as  can  be  seen  by  a  study  of  pi.  3,  fig.  5. 

Outcrops  of  Folded  Mineral  Beds. — The  peculiarities 
of  the  outcrops  of  bedded  deposits,  when  there  has  been 
folding  of  the  strata,  are  well  illustrated  in  pi.  4,  figs. 
1,  2,  3  (after  Geikie),  and  should  be  carefully  studied 
by  those  making  locations  of  iron  or  coal  deposits,  as 
they  may  lead  to  wild  conclusions  as  to  the  amount  of 
ore  or  coal  in  the  surface  exposures.  Figs.  2  and  3 
show  how,  by  lateral  pressure,  the  beds  laid  down 
horizontally  have  been  squeezed  until  any  one  of  them 
presents  the  appearance  of  a  piece  of  corrugated  iron, 
or  the  troughs  and  crests  of  a  series  of  waves.  By  the 
wearing  away  of  the  surface  of  such  a  folded  mass  the 
edges  or  outcrops  of  the  different  strata  would  be 
exposed  as  in  fig.  1,  of  which  fig.  2  is  a  cross  section 
on  the  line  O  H,  and  fig.  3  on  the  line  C  D  B.  B 
forms  the  synclinal  and  A,  A,  the  anticlinal  fold  of  the 
exposure,  the  different  beds  of  which  are  numbered  so 
as  to  be  recognizable  in  each  of  the  figures.  The  dotted 
lines  in  figs.  2  and  3  indicate  the  position  of  that  por- 
tion of  the  folds  which  has  been  worn  away.  Now,  if 
we  suppose  the  heavy  black  line  between  12  and  13  to 
be  a  deposit  of  iron  ore,  it  is  morally  certain  that  the 
majority  of  prospectors  would  report  two  veins  forking 
at  By  pi.  13,  fig.  1,  when  instead  of  two  veins,  presum- 
ably dipping  into  the  ground  to  unknown  depths, 
there  is  merely  a  trough  lying  between  the  two  out- 
crops, the  boundaries  of  which  can  be  absolutely 
measured  and  the  area  calculated  similarly  at  A  4,  fig. 
1,  two  veins  would  be  reported  forking  in  a  similar 
manner,  whereas  it  is  merely  the  same  sinuous  dipping 
away  in  all  directions  to  unknown  depths,  and  conse- 
quently more  extensive  than  the  beds  B,B,  but  more 
difficult  of  access,  and  to  be  found  below  B,  B  if  not 
buried  too  deeply  under  the  strata  5  to  12  inclusive, 
to  be  reached  by  shafts.  These  remarks  are  intended 


148         PROSPECTING  AND  VALUING  MINES. 

to  direct  the  attention  of  the  prospector  to  the  neces- 
sity of  ascertaining  the  dip  of  such  discoveries  at  the 
earliest  possible  moment,  as  a  simple  matter  of  self- 
protection,  so  that  he  may  locate  the  requisite  adja- 
cent ground  and  prevent  others  from  gathering  the 
larger  share  of  the  fruits  of  his  labors.  Even  the 
simplest  tilting  of  a  series  of  strata,  combined  with 
exposure  of  the  outcrop  by  one  stream  running  with 
the  dip  and  another  across  it,  may  present  the  appear- 
ance of  cross  veins,  particularly  if  some  portions  of 
the  outcrop  are  covered  with  debris  in  such  a  way  that 
it  is  not  visible  for  its  full  length. 

Caves,  etc. — Where  ore  is  found  outside  of  fissure 
veins  or  contacts,  the  influence  of  the  rock  on  the  form 
of  the  deposit  is  yet  more  strongly  marked.  We  have 
noted  the  influence  which  slates  exert  on  lodes,  con- 
verting them  rather  into  metalliferous  bands  of  rock. 
Limestones  stamp  their  character  upon  the  ore  bodies 
by  the  formation  of  chambers  connected  together  by 
thin  seams  or  pipes.  However  irregular  the  series  of 
chambers  may  be,  they  must  have  been  formed  by  cir- 
culating waters  (descending  in  the  example  shown  by 
the  arrowheads  in  pi.  6,  fig.  8)  which  followed  the  bed- 
ding planes  or  joints,  and  we  must  consequently  take 
these  as  our  guides  when  searching  for  the  continua- 
tion of  an  exhausted  chamber. 

In  this  connection  it  is  instructive  to  note  the  great 
similarity  between  a  map  of  the  workings  of  the  lime- 
stone contact  lodes  of  Leadville  and  one  of  tortuous 
chambers  of  the  Mammoth  Cave  in  Kentucky,  carved 
out  of  limestone  by  the  action  of  water,  the  only 
apparent  difference  between  them  being  that  one  set 
of  chambers  has  been  filled  with  ore  and  the  other  has 
remained  open.  The  latter  fact  is  further  of  interest 
as  showing  that  it  is  possible  for  underground  open- 
ings of  large  size  to  exist,  as  opposed  to  the  theory 
advanced  by  some  w?riters  that  such  caves  are  impos- 
sible along  the  lines  of  a  fissure  on  account  of  the 


MINERAL  DEPOSITS  OTHER  THAN  VEINS.     149 

enormous  pressure  of  the  surrounding  earth  mass,  and 
that  consequently  all  veins  must  be  formed  by  gradual 
substitution  of  one  mineral  for  another,  at  the  time  of 
removal.  Many  deposits  are,  however,  undoubtedly 
formed  by  the  substitution  process. 

Coal  and  Auriferous  Gravel  Beds. — Discussion  of 
these  deposits  is  reserved  for  Chaps.  XY  and  XVI, 
respectively.  " Masses"  are  noticed  in  Chap.  IV.,  p. 
81;  "gash  veins"  and  "segregations"  in  Chapter 
V0,  p.  95. 


CHAPTEB   IX. 

PROSPECTING. 

Discretion  in  Taking  up  Ground. — Fortunate  is  the 
man  who  has  the  instinctive  ability  to  recognize  a 
"mine"  when  he  sees  it,  and  the  courage  to  forbear 
locating  every  little  seam  of  ore  he  may  encounter. 
Nearly  every  prospector  is  "location  poor;"  loaded  up 
with  so-called  mines,  the  bulk  of  which  should  never 
have  been  located;  which  he  is  confessedly  unable  to 
work,  and  many  of  which  were  simply  considered 
"good  enough  to  sell"  when  the  notice  of  location  was 
pasted.  As  a  general  thing,  nothing  is  worth  locat- 
ing, and  it  is  only  in  exceptional  cases  that  anything 
is  worth  working,  which  has  not  a  first-class  surface 
showing  either  in  quantity  or  quality  of  ore.  "Ex- 
tensions" of  good  and  proved  mines  may  be  excep- 
tions. 

Accurate  Observation  and  Description. — It  is  a  com- 
mon remark  among  prospectors,  when  the  surface 
showing  is  not  particularly  promising,  that  it  is  only 
necessary  to  gain  depth  to  make  a  mine.  We  shall 
soon  see  that  there  is  no  foundation  for  such  a  state- 
ment, when  we  come  to  consider  the  lesson  of  the  out- 
crop. But  first  let  us  look  at  the  points  which  a  pros- 
pector should  note  about  each  of  his  locations  as  they 
are  made,  so  that  he  may  be  able  to  intelligently 
explain  their  condition  to  those  whose  aid  he  may 
desire  to  develop  them,  remembering  that  all  ques- 
tions which  can  be  answered  positively  should  be  so 
answered,  and  that  on  all  other  points  an  underesti- 
mate is  infinitely  better  than  an  overstatement.  If  a 


PROSPECTING.  151 

man  examining  a  mine  for  investment  finds  the  repre- 
sentations honestly  and  accurately  made,  the  first  im- 
pression (always  an  important  one)  is  favorable  and 
likely  to  remain ;  but  if  first  one  discrepancy  and  then 
another  is  encountered,  a  feeling  of  distrust  is  created 
which  may  break  off  pending  negotiations,  while  at 
the  same  time  there  has  been  no  intention  on  the  part 
of  the  owners  to  make  a  rnisstatement  of  facts.  The 
trouble  frequently  arises  from  the  use  of  terms  in  a 
loose  way,  so  that  they  convey  to  the  hearer  a  totally 
different  impression  from  that  intended  by  the  speaker ; 
or  it  may  be  altogether  from  a  want  of  knowledge  or 
misapprehension  of  the  meaning  of  certain  facts. 

POINTS    TO    BE    DETERMINED. 

1.  DISTANCE  FOE  WHICH  THE  VEIN  on  DEPOSIT  CAN  BE 
TRACED.— Not  infrequently  we  are  told  that  the  vein 
can  be  traced  a  mile,  when  in  reality  there  are  only  a 
series  of  isolated  outcrops  in  a  more  or  less  straight 
line,  with  intermediate  barren  or  apparently  barren 
spaces,  often  of  considerable  extent.  Strictly  speak- 
ing,the  distance  for  which  the  outcrop  can  be  followed 
without  a  break  is  all  that  should  be  called  traced,  but 
if  the  vein  lie  at  the  contact  of  two  different  kinds  of 
rock,  and  on  following  this  line  of  junction,  even 
when  no  vein  matter  is  visible,  a  second  outcrop  be 
found  on  the  contact,  both  outcrops  may  fairly  be  con- 
sidered as  on  the  same  lode.  The  same  will  be  the 
case  if  the  vein  is  formed  on  the  wall  of  a  dike,  in 
which  case  all  ore  bodies  lying  on  the  same  side  of  the 
dike  may  be  called  parts  of  the  same  vein.  But  as  it 
seldom  if  ever  happens  that  the  vein  for  its  whole 
length  is  ore-bearing,  the  distance  the  vein  itself  can  be 
traced  is  of  vastly  less  importance  (except  as  indicat- 
ing its  strength  and  probable  continuance  in  depth) 
than  the  distance  the  ore  body, the  really  essential  part 
of  the  vein,  can  be  followed  unbroken.  This  length 
should  be  determined  even  if  it  takes  some  trouble. 


152         PROSPECTING  AND   VALUING  MINES 

Following  Dikes  and  Contacts. — In  tracing  an  out- 
crop, or  rather  a  vein,  nature  offers  many  indications. 
If  following  a  dike,  the  latter  is  generally  much  larger 
than  the  vein  and  not  infrequently  harder  than  the 
rocks  which  it  traverses,  standing  up  above  them,  and 
can  be  taken  as  a  guide.  If  the  vein  is  on  the  contact 
of  two  rocks,  and  covered  in  places  with  earth  or 
debris,  it  is  only  necessary  to  locate  outcrops  of  the 
rocks  on  each  side  of  the  contact,  and  the  search  may 
safely  be  confined  to  the  space  between  them.  Nar- 
row trenches  through  the  surface  dirt,  run  across  the 
general  line  of  the  lode,  will  easily  locate  the  contact 
and  disclose  the  ore  if  it  exists.  The  process  is  called 
"costeaning"  by  the  Cornish  miners. 

Vegetation  as  a  Guide. — Sometimes  the  vegetation 
on  the  two  different  rocks,  especially  when  decidedly 
unlike  in  composition,  is  so  different  that  the  line  of 
contact  may  be  traced  by  it  alone.  In  open  countries 
free  from  heavy  timber,  like  Arizona,  this  is  strikingly 
the  case.  Probably  the  most  distinctive  vegetation 
in  those  localities  is  the  various  forms  of  "yucca, "  of 
which  the  "Spanish  bayonet"  is  a  sample;  and  the 
"ocotilla"  (o-ko-te-ya).  The  yucca  is  confined  to  the 
granite  or  quartzite  rocks,  evidently  liking  a  soil 
abounding  in  silica  (quartz);  the  ocotilla  is  as  de- 
cidedly confined  to  the  clay-slate  regions,  the  line  of 
contact  being  often  drawn  on  a  hillside  by  these  two 
plants  as  if  defined  by  a  fence;  while  the  cactus  fre- 
quents the  limestone  outcrops  and  the  areas  of  erup- 
tive rocks.  In  other  words,  for  successful  growth,  the 
yuccas  require  quartz,  the  ocotilla  clay, and  the  cactus 
lime.  In  the  broad  washes  or  beds  of  summer  tor- 
rents, called  "arroyos, "  where  the  rocks  are  mixed, 
all  three  may  be  found  growing  if  the  debris  is  of  a 
suitable  character. 

A  fissure  may  also  be  defined  by  the  vegetation 
growing  on  it  being  different  in  character,  or  a  line  of 
contact  may  be  traced  by  the  same  means,  as  in  Cali- 


PROSPECTING.  153 

fornia,  where  the  rim  rock  of  the  gravel  channels, 
even  where  covered  and  obscured  by  dense  brush 
(chaparral)  can  be  followed  along  the  mountain  side 
by  the  elderberry  bushes,  the  white  flowers  of  which 
are  very  conspicuous  in  the  gray  brush  in  spring. 
These  bushes  require  permanent  water  and  have 
located  themselves  along  the  bed  rock  rim  where 
the  water  in  the  gravel  flows  over  it  or  on  the  top  of 
the  pipe-clay  just  below  the  lava  cap. 

Springs. — -A  lost  vein  may  not  infrequently  be 
picked  up  again  by  examining  the  springs  along  the 
line  of  its  general  direction,  as  the  extent  of  the  fis- 
sure converts  it  into  the  most  available  underground 
water-course,  which  gives  up  its  supply  as  a  spring, 
if  a  ravine  has  cut  down  across  it,  to  the  permanent 
water  level  of  the  lode. 

2.  THICKNESS  OF  THE  VEIN. — Here  again  there  is 
often  a  confusion  of  the  vein  and  the  ore  body.  It  is 
the  thickness  of  the  latter  which  is  the  important  item 
to  the  intending  investor;  the  total  width  of  the  fis- 
sure is  only  of  interest  as  suggesting  a  possibility  that 
at  some  point  or  other  it  may  be  completely  filled  with 
ore. 

How  Measured. — While  the  thickness  of  the  ore 
body  may  be  accurately  measured  at  as  many  points 
as  may  be  deemed  desirable  to  get  a  fair  average,  the 
width  of  the  vein  (by  which  is  meant  the  distance  be- 
tween the  walls  at  right  angles  to  them,  not  horizon- 
tally) may  be  very  difficult  to  ascertain,  and  many 
statements  are  made  on  this  score  with  the  best  inten- 
tions, which  are  misleading,  because  the  parties  have 
no  true  idea  as  to  what  really  constitutes  the  vein. 

Total  Width  and  Ore  Thickness. — On  the  Comstock 
lode  the  distance  between  the  east  and  west  walls  on 
the  surface  in  the  Savage  mine  was  fully  1,000  ft.,  of 
which  only  a  small  part  was  quartz  and  of  that  only  a 
portion  was  available  ore.  The  width  was  about  the 
same  at  the  Chollar-Potasi  mine,  some  1,600  ft.  to  the 


154         PROSPECTING  AND  VALUING  MINES. 

south,  with  several  quartz  bodies  cropping  parallel  to 
each  other,  of  which  pi.  2,  fig.  2,  will  give  a  fair  idea 
in  cross  section.  These  were  at  first  supposed  to  be 
separate  veins,  but  at  about  330  ft.  below  the  croppings 
the  Savage  mine  was  reduced  to  a  width  of  800  ft., 
nearly  all  waste  matter;  and  the  Chollar-Potasi  mine 
to  a  width  of  150  ft.,  all  quartz,  of  which  about  one- 
quarter  was  ore. 

Veins  on  Dikes. — In  cases  where  the  ore  forms  on 
the  walls  of  a  porphyry  dike  (as  in  many  of  the  mines 
of  the  Monte  Cristo  district,  in  Washington),  the 
prospector  generally  calls  the  entire  dike  the  vein, 
giving  it  a  width  of  from  20  to  SO  ft.  or  over,  because 
he  may  be  able  to  find  traces  of  iron  pyrite  in  the 
more  decomposed  portions  of  the  dike,  the  bulk  of 
which  is,  however,  unaltered  rock.  Obviously  the 
vein  is  only  that  portion  of  the  decomposed  dike 
which  has  been  replaced  by  ore.  To  give  the  entire 
width  of  the  dike  as  the  vein,  will  create  a  very  seri- 
ous misunderstanding,as  it  is  scarcely  probable  that  it 
will  have  been  converted  to  an  ore  body  for  its  full 
thickness,  at  any  point  of  its  length. 

False  and  Indistinct  Walls. — In  other  cases,  where 
there  has  been  much  motion  in  the  fissure,  its  walls 
may  have  become  much  shattered  and  rotten,  forming  a 
series  of  slabs,  each  of  which  may  present  the  smooth 
face  of  a  true  wall,  even  to  the  slickensides,  but  which 
will  peel  off  one  after  the  other,  after  a  short  exposure 
to  the  air,  making  it  difficult  to  state  positively  when 
the  true  wall  is  reached 

In  slatey  rocks  there  may  be  one  wall  well  defined  (if 
the  vein  is  a  contact)  while  parallel  bodies  of  ore  or 
barren  ganglia  may  lie  in  the  slates  for  several  hun- 
dred feet  from  the  contact  (pi.  6,  fig.  1),  as  in  the 
mother  lode  of  California.  Under  these  circumstances 
it  is  better  to  give  the  width  of  the  ore,  and  if  there  is 
a  decided  difference  in  its  appearance,  the  width  of 
each  portion,  taking  samples  as  described  in  Chapter 
II. 


PROSPECTING,  155 

If  the  length  and  width  of  the  ore  bodies  as  they 
show  on  the  surface  were  ascertained  in  this  manner,  a 
large  number  of  locations  would  be  abandoned,  having 
failed  to  stand  the  test  of  working  value;  and  while 
the  prospector  would  have  fewer  locations  on  his 
hands,  he  would  be  saved  the  burden  of  the  annual 
assessment  work  on  worthless  properties,  and  he  could 
.honestly  ask  capital  to  aid  the  development  of  those 
so  carefully  selected. 

3.  SAMPLES  or  THE  COUNTRY  EOCK. — While  a  study 
of  the  chapter  on  rocks  will  have  enabled  even  a 
beginner  to  speak  of  them  with  something  like  accu- 
racy, it  would  be  well  to  take  a  small  hand  sample  of 
the  rock  on  each  side  of  the  vein.  We  have  seen  what 
important  differences  there  are  in  the  shape  of  deposits 
in  different  rocks,  and  one  of  the  first  questions  an 
expert  will  ask  is  on  this  subject,  as  it  affects  also  the 
cost  of  working  most  seriously,  a  drift  or  shaft  in  soft 
slate  costing  very  much  less  than  one  in  hard  granite. 
Should  there  be  a  doubt  as  to  the  judgment  or  knowl- 
edge of  the  prospector  the  specimens  will  speak  for 
themselves,  and  are  nearly  as  important  as  the  ore 
samples.  These  samples  need  not  be  taken  immedi- 
ately from  the  walls  themselves,  as  in  such  places  the 
rocks  are  usually  greatly  decayed  and  unrecognizable  in 
small  pieces.  It  is  better  to  take  them  a  little  dis- 
tance from  the  vein  (say  from  the  nearest  outcrop  in 
place),  as  these  are  likely  to  be  solid,  being  harder 
than  their  neighbors,  and  while  taking  these  samples 
to  note  whether  the  outcrop  of  the  vein  occurs  in  a 
country  which  is  badly  broken  up,  or  whether  the 
hills  are  large  and  smooth.  The  latter  appearance 
promises  better  than  the  former  for  a  solid  continuous 
vein  without  displacements.  In  selecting  specimens 
the  prospector  should  also  ascertain  whether  the  vein 
runs  parallel  to  the  general  direction  of  the  rocks,  or 
whether  it  cuts  across  the  formation — features  which 
have  an  important  influence  on  the  probable  perma- 


156         PROSPECTING  AND  VALUING  MINES. 

nence  of  the  lode  in  depth,  the  latter  structure  almost 
necessarily  involving  a  deep  fissure  of  considerable 
length  as  well  as  depth. 

The  names  of  even  the  common  rocks  seem  to  be  a 
continual  stumbling  block  to  most  prospectors,  appar- 
ently for  no  other  reason  than  a  failure  to  realize  the 
fact  that  each  kind  is  made  up  of  a  definite  combina- 
tion of  a  few  minerals.  It  would  seem  as  though  the 
trouble  of  learning  to  distinguish  from  ten  to  twenty 
kinds,  which  is  about  all  that  is  necessary,  ought  not 
to  be  such  a  serious  matter.  Every  business  has  its 
own  language,  and  those  who  wish  to  excel  must 
necessarily  learn  to  speak  in  a  language  which  will 
convey  the  same  idea  to  all  hearers,  and  each  word  of 
which  will  convey  a  positive  idea,  instead  of  a  hazy 
nothing.  The  writer  recently  met  a  prospector  who 
had  some  fair-looking  specimens  of  ore,  but  when 
questioned  about  the  mode  of  occurrence  and  the  lay 
of  the  country,  in  an  effort  to  get  an  idea  of  the  facili- 
ties for  working,  in  reply  to  a  question  as  to  whether 
it  was  a  granite  country  he  answered  "Yes."  When 
asked  if  there  was  slate,  "yes"  was  the  reply.  And 
to  fully  satisfj7  any  further  inquiries  which  might  be 
made  for  other  rocks  he  added,  "There  is  a  regular 
jumble  of  them!"  If  this  was  really  the  case  he  had 
condemned  his  property,  as  such  a  condition  neces- 
sarily involved  a  badly  broken  country,  but  it  was 
evident  that  he  knew  nothing  about  the  subject  under 
discussion,  while  he  simply  cast  a  doubt  upon  every 
other  statement  he  had  made,  showing  that  he  was 
not  a  good  observer.  To  make  things  worse  he  subse- 
quently inquired  what  basalt  was  worth,  and  when  in- 
formed that  it  was  merely  a  black  volcanic  rock  with- 
out value  for  any  of  the  precious  metals,  he  gently 
intimated  that  his  informant  might  know  what  he  was 
talking  about,  but  that  he  had  his  own  opinion  on  the 
subject.  His  basalt  proved  to  be  orpiment,  a  yellow 
compound  of  arsenic  and  sulphur. 


PROSPECTING.  157 

4.  FACILITIES  FOE  WORKING. — The  faculty  of  locality, 
which  must  be  well  developed  in  a  prospector  to 
enable  him  to  find  his  wajr  through  the  wilderness, 
will  usually  also  enable  him  to  describe  the  best 
routes  of  access  to  his  property  and  what  can  be  done 
or  has  been  done  in  the  way  of  trails  and  roads.  It 
will  also  enable  him  to  answer  questions  as  to  the 
supply  of  timber  for  mining  purposes  (a  most  impor- 
tant item)  and  for  fuel,  if  coal  is  not  accessible,  so 
that  the  water  supply  and  the  chances  for  economical 
development  are  the  only  questions  to  which  we  need 
allude  in  detail  under  this  heading.  If  fuel  is  scarce 
and  water  abundant,  the  latter  may  furnish  the  motive 
power  if  the  supply  can  be  used  under  pressure,  either 
directly  or  through  the  use  of  electricity,  and  to  enable 
the  prospector  to  readily  estimate  this  power,  a  short 
chapter  has  been  devoted  to  the  measurement  of 
water,  and  the  method  of  calculating  the  horse  power 
which  a  given  quantity  will  develop.  This  depends 
on  the  quantity  and  the  fall  which  can  be  secured, 
modified  slightly  by  the  distance  it  has  to  be  taken  to 
secure  the  fall,  so  that  the  prospector  should  be  able 
to  answer  these  questions  approximately.  A  measure- 
ment of  the  supply  taken  in  the  dry  season  is  most 
desirable  as  giving  the  supply  which  can  be  depended 
on  all  through  the  year  without  the  use  of  reservoirs, 
which  are  costly  and  often  impracticable. 

In  not  a  few  mining  camps  water  is  scarce  during 
the  early  stages  of  development,  but  while  this 
scarcity  may  increase  the  cost  of  the  earlier  work,  the 
defect  is  one  that  usually  remedies  itself  before  any 
considerable  depth  has  been  attained,  an  abundant 
supply  being  generally  secured  from  the  shafts  and 
tunnels,  even  if  the  quantity  does  not  prove  excessive 
— as  in  Tombstone,  Ariz.,  which  in  early  days  was  a 
notoriously  dry  camp. 

The  manner  in  which  the  vein  can  be  opened  to  the 
best  advantage  will  depend  on  the  shape  of  the  coun- 


158         PROSPECTING  AND  VALUING  MINES. 

try  and  the  way  the  vein  crosses  it.  If  flat,  shafts 
must  bo  resorted  to;  if  hilly,  it  may  be  better  to  adopt 
tunnels  if  they  can  be  run  on  the  vein,  and  the  pros- 
pector should  inform  himself  thoroughly  whether  this 
can  be  done  to  advantage,  which  will  depend  on  the 
position  of  the  outcrop.  This  question  is  more  fully 
treated  in  Chapter  XII.,  on  early  development,  and 
attention  is  merely  called  to  it  here,  as  one  of  the 
things  on  which  all  possible  information  should  be 
acquired. 

5.  LESSON  OF  THE  OUTCROP. — All  the  foregoing 
remarks  apply  only  to  the  surface  observations,  but  in 
studying  the  outcrop  we  may  gain  some  insight  into 
the  probabilities  of  depth. 

Present  Appearance  not  the  Original — The  first 
necessity  is  to  disabuse  the  mind  of  the  idea  that  the 
veins  were  all  formed  after  the  country  had  assumed 
very  much  its  present  shape  and  appearance.  The 
remark  so  commonly  made,  that  a  vein  which  shows 
poorly  on  the  surface  will  improve  with  depth,  is 
based  on  this  fallacy,  the  underlying  idea  evidently 
being,  although  probably  not  even  thought  out  in  the 
mind  of  the  speaker,  that  the  ore  at  that  particular  spot 
had  not  been  able  to  reach  the  surface,  a  notion  as- 
sisted by  the  other  false  idea  that  all  the  filling  of  the 
veins  had  been  squeezed  into  them  from  below. 

As  a  matter  of  fact  there  has  been  an  immense 
change  in  the  surface  since  the  majority  of  the  min- 
eral deposits  were  formed.  In  the  case  of  coal  fields 
originally  laid  down  horizontally  and  subsequently 
tilted  to  steep  angles,  whole  sections  of  these  fields 
have  been  worn  away  along  with  the  inclosing  rocks, 
or  we  should  have  no  outcrop  of  them.  In  California 
we  have  absolute  proof  that  the  rocks  which  carry  the 
gold  veins  have  been  worn  away  in  places,  even  since 
the  eruption  of  the  basalt  lavas  which  filled  and  cov- 
ered up  the  old  river  channels  to  a  depth  of  fully 
2,000  ft.,  as  in  the  canons  of  Slate  Creek,  Canon  Creek 


PHOSPECTING.  159 

and  others  in  Sierra  and  Plumas  counties.  As  these 
old  river  channels  carr.y  gold,  in  fully  as  great  a  quan- 
tity as  the  modern  placers,  which  must  have  been 
derived  from  the  wear  and  tear  of  the  hills  which 
formed  their  flanks,  there  must  have  been  extensive 
erosion  before  the  flow  of  the  lava,  to  carve  out  these 
immense  valleys,  so  that  we  may  add  an  unknown 
quantity  to  the  known  2,000  ft.,  and  probably  be 
within  limits  if  we  estimate  the  degradation  of  the 
mountains  carrying  the  gold  veins  at  4, 000  ft.  or  over. 
Writers  on  Abyssinia  state  that  in  the  approach  to 
Magdala  gorges  4,000  ft.  deep  have  been  cut  down 
through  the  basalt  into  the  underlying  rocks,  leaving 
the  basalt  as  table  lands,  much  as  in  California,  and 
if  gold  veins  traversed  the  rocks  of  the  Grand  Canon 
of  the  Colorado  we  should  have  their  secrets  exposed 
3,000  ft.  below  the  top  of  the  plateau,  through  which 
the  river  has  carved  its  stupendous  gorge.  It  is  there- 
fore evident  that  in  the  great  majority  of  cases  the 
outcrops  of  veins  may  be  called  purely  accidental  ex- 
posures, which  have  been  constantly  changing  in  their 
appearance  for  thousands  of  years. 

Increase  or  Decrease  in  Depth. — The  erosion  or 
wear  and  tear  by  air  and  water  may  have  proceeded 
just  far  enough  to  uncover  the  top  of  the  ore  body,  or 
it  may  have  progressed  so  far  that  nearly  all  of  it  may 
have  been  removed.  Are  there  any  evidences  in  the 
outcrops  themselves  as  to  which  stage  has  been 
reached?  Before  entering  on  this  question,  however, 
let  us  look  at  the  probable  increase  or  decrease  in  the 
value  of  the  ore  in  depth. 

In  the  case  of  veins  which  carry  large  quantities  of 
sulphuretted  ores  which  are  easily  decomposed,  such 
as  iron  and  copper  pyrites,  we  may  expect  a  decrease 
in  value  on  reaching  the  permanent  water  level  of  the 
mine,  below  which  the  decomposition  will  not  have 
extended.  If  these  iron  pyrites  carry  gold,  the  gold 
will  have  been  liberated  by  their  decomposition,  and 


160        PROSPECTING  AND  VALUING  MINES. 

will  accumulate  in  the  cavities  of  the  rusty  quartz; 
and  as  the  ore  after  the  removal  of  its  sulphur  and 
part  of  the  iron  is  lighter,  bulk  for  bulk,  than  the 
uudecomposed  sulphides  below,  we  have  a  greater 
bulk  to  the  ton  and  also  an  enriched  material,  so  that 
assays  of  the  croppings  are  likely  to  be  better  than 
can  be  had  after  the  water  level  is  reached. 

In  copper  veins  the  decomposition  of  the  copper 
pyrite  results  in  the  formation  of  the  red  and  black 
oxides  of  copper  (just  as  in  the  former  case  the  product 
of  decomposition  was  oxide  of  iron)  both  of  which  are 
richer  in  copper  per  ton  than  the  sulphide;  and  as 
they  are  practically  concentrated  surface  deposits,  not 
extending  below  the  water  line,  and  may  result  from 
the  decay  and  leaching  of  very  poor  ores,  we  have 
another  instance  in  which  the  vein  would  be  poorer  in 
depth. 

But  where  no  decomposition  has  taken  place  there 
is  little  or  no  proof  of  continuous  improvement  in 
depth,  and  more  probability  of  impoverishment  of  the 
vein.  If  the  former  were  the  case  the  improvement 
ought  to  be  continuous  and  there  would  be  no  limit  to 
the  increase  of  the  deposit,  which  we  know  not  to  be 
the  case ;  and  it  is  more  than  likely  that  the  quality  of 
ore  varies  greatly  in  nearly  all  instances,  sometimes 
improving  and  sometimes  growing  poorer  as  the  earth 
is  penetrated,  being  governed  very  largely  by  changes 
in  the  character  of  the  rocks  traversed  by  the  vein,  and 
accidental  conditions  which  we  have  not  yet  learned 
to  realize  and  understand. 

But  the  prospector  need  be  in  no  doubt  on  this 
point,  as  in  most  cases  he  can  satisfy  himself  from 
personal  examination  as  to  the  facts.  If,  as  has  been 
stated,  the  deposits  were  formed  when  the  country  was 
more  elevated  than  at  present,  any  ravine  cutting 
across  a  vein  or  deposit  explores  it  naturally  as  we  do 
artificially  by  sinking  a  shaft,  and  if  improvement  fol- 
lows with  increased  depth,  the  outcrop  at  the  bottom 


PROSPECTING.  161 

of  the  ravine  ought  to  be  richer  than  one  on  the  sum- 
mit, as  a  descent  of  100  ft.  vertically  below  the  top  of 
the  ridge  would  be  equal  to  the  100  ft.  level  of  a  shaft 
sunk  on  the  outcrop — 200  ft.  would  equal  the  200  ft. 
level,and  so  on.  How  little  this  accords  with  experi- 
ence every  prospector  knows. 

Nothing  but  actual  work  can  positively  determine 
the  question  whether  we  have  merely  the  top  or  the 
tail  end  of  an  ore  body,  as  if  we  look  upon  the  ore 
body  as  a  roughly  shaped  lens,  two  parallel  lines 
drawn  through  it,  one  just  below  the  top  and  the 
other  just  above  the  bottom,  would  each  cut  off.  a  por- 
tion showing  the  same  width  and  length;  but  if  the 
ore  is  softer  than  the  inclosing  rock,  and  the  vein 
crops  in  the  bottom  of  a  deep  gorge,  there  is  every 
probability  that  the  gorge  has  been  formed  by  the 
wearing  down  and  removal  of  the  ore  body,  that  the 
outcrop  found,  if  of  small  dimensions,  is  merely  the 
lower  end  where  the  increased  portion  of  country  rock 
resisted  the  action  of  the  stream  to  a  larger  extent  and 
stopped  further  erosion.  In  a  similar  way,  if  the  out- 
crop is  on  a  steep  hillside  and  of  only  limited  length, 
it  may  in  many  cases  indicate  the  termination  of  the 
ore  body,  as  the  erosion  of  the  ravine  which  has  ex- 
posed it  has  also  disclosed  some  of  the  secrets  of  its 
penetration  in  depth,  as  just  described  in  discussing 
the  quality.  But  if  the  outcrop  is  of  considerable 
length  and  thickness,  this  question  need  not  trouble 
us,  as  there  is  sufficient  justification  for  the  expendi- 
ture of  considerable  money  in  development. 

The  condition  of  the  mineral  in  the  outcrop  may 
also  furnish  a  slight  guide  as  to  probable  permanence 
in  depth.  Some  of  the  common  minerals  in  ore, 
especially  the  several  varieties  of  pyrite,  are  easily  de- 
composed under  exposure  to  air  and  water,  and  where 
there  is  evidence  in  the  rustiness  of  the  outcrop,  or 
the  presence  of  a  spongy  looking  mass  from  which  the 
crystals  have  been  perfectly  removed,  we  may  cer- 


162        PROSPECTING  AND  VALUING  MINES. 

tainly  infer  that  the  drainage  of  the  vein  extends  to 
some  depth  and  involves  a  continuous  fissure,  as  it  is 
only  by  the  presence  of  such  conditions  that  the  de- 
composition could  have  been  effected.  But  if  the 
pyrites  remain  in  the  croppings  entirely  undecom- 
posed,  we  may  infer  that  the  walls  of  the  fissure  are  so 
tightly  in  contact  below  as  to  prevent  the  percolation 
or  seepage  of  water  downward,  and  this  may  be  taken 
as  an  unfavorable  sign. 

In  soft  and  easily  decomposed  ore  bodies  the 
removal  of  the  outcrop  running  along  the  face  of  a 
hill,  instead  of  across  it  may  result  in  shallow  depres- 
sions, instead  of  a  conspicuous  ridge,  in  which  the 
ore  can  only  be  found  by  digging;  and  when  the  ore 
is  of  this  character,  the  search  for  it  becomes  a  very 
laborious  task,  especially  in  moist  and  wooded  coun- 
tries, where  the  vegetation  may  be  exceedingly  rank 
and  tangled. 

Float. — From  what  has  been  said  of  the  origin  of 
veins  and  the  subsequent  carving  out  of  the  ravines 
and  valleys  as  they  exist  to-day,  it  is  evident  that  there 
must  be  on  the  hillsides  and  in  the  ravines  of  a  coun- 
try rich  in  minerals,  many  fragments  of  mineral 
detached  from  the  ore  bodies.  These  are  called 
"float,"  and  it  is  equally  evident  that  the  harder  the 
material  forming  the  gangue  of  the  ore,  the  larger 
should  be  the  number  of  fragments  which  have  escaped 
the  destructive  action  of  air,  frost,  water  and  sun- 
shine. Such  minerals  as  decompose  very  readily,  or 
are  excessively  brittle,  may  disappear  altogether,  or 
nearly  so,  as  coal  or  some  forms  of  galena;  but  quartz- 
ose  varieties  may  survive  a  long  journey  and  be  found 
at  considerable  distances  from  their  original  source. 
Large  fragments  indicate  this  source  to  be  much 
nearer  than  small  ones.  Gravity  has  constantly  car- 
ried these  fragments  to  a  level  lower  than  their  source, 
so  that  when  tracing  float,  as  so  often  done,  we  look 
for  this  source  above  the  place  at  which  the  float  has 


PROSPECTING.  163 

been  found.  It  may  have  reached  this  place  either  by 
rolling  down  the  hillside  in  the  immediate  neighbor- 
hood, or  it  may  have  been  carried  down  the  bed  of  the 
ravine  by  water.  The  position  of  the  float  will  gen- 
erally indicate  which  has  been  the  method  of  trans- 
port, but  in  either  case  we  must  trace  it  upward,  and 
if  we  find  the  fragments  increasing  both  in  number 
and  in  size,  we  may  conclude  that  we  are  nearing  the 
source  of  supply.  Sometimes  these  may  lead  to  the 
discovery  of  well-defined  lodes,  and  again,  in  the  case 
of  quartz,  we  may  finally  lose  all  trace  of  it,  without 
encountering  anything  of  value.  This  is  especially 
apt  to  be  the  case  in  slate  countries,  which  have  been 
crushed  and  crumpled  and  subsequently  filled  with 
innumerable  thin-  quartz  seams.  All  the  float  may 
have  been  derived  from  these  seams,  and  the  float 
ceases  because  we  have  reached  the  limit  of  the  slate 
formation,  and  enter  a  new  series  of  rocks  without 
quartz.  This  structure  explains  numbers  of  cases  of 
"lost  leads,"  but  while  there  may  be  no  well-defined 
vein  or  lode  at  the  point  where  the  ravine  cuts  the 
formation,  if  metal  has  been  found  in  the  float  it 
shows  that  the  region  is  worth  prospecting  and  the 
search  should  be  continued  along  the  line  of  contact 
of  the  rock  which  has  cut  out  the  metal-bearing  series. 
Topography  and  Water  System. — The  reverse  is 
just  as  likely  to  be  the  case  where  the  ore  body  is  soft, 
as  nature  always  carves  out  a  country  on  the  lines  of 
least  resistance,  which  may  be  lines  of  faulting,  or 
contact  of  a  soft  and  a  hard  rock,  or  through  soft  ore 
bodies  or  between  consolidated  hard  ones.  For  this 
reason  the  study  of  the  water  system  of  any  particular 
mountain  region  affords  a  good  insight  into  its  phys- 
ical structure.  If  all  rocks  were  of  uniform  and  equal 
hardness,  the  face  of  a  country  would  be  planed  down 
to  uniform  smooth  slopes.  It  is  the  varying  resist- 
ance of  rocks  which  diversifies  the  mountain  regions, 
in  combination  with  the  dislocations  they  have  under- 
gone. 


164        PROSPECTING  AND  VALUING  MINES. 

GENERAL    HINTS. 

What  to  Look  for. — The  importance  to  the  prospec- 
tor of  knowing  something  about  rocks  becomes  appar- 
ent. In  a  granite  country  it  is  evident  that  he  may 
expect  tin  as  well  as  a  variety  of  other  minerals,  and 
should  consequently  know  the  ores  of  tin  (and  they 
often  do  not  look  like  metallic  ores)  so  as  to  be  able  to 
recognize  them.  In  a  limestone  belt,  galena,  iron  and 
zinc  are  specialities.  In  a  country  made  up  of  vol- 
canic and  eruptive  rocks,  it  is  useless  to  look  for  coal; 
but  in  such  a  country,  where  a  belt  of  hot  springs 
follow  the  junction  of  eruptive  rocks,  especially  basalt, 
with  a  group  of  sedimentary  strata,  the  ores  of  quick- 
silver should  be  in  his  mind.  In  a  belt  of  hornblende 
rocks  he  may  devote  his  energies  to  asbestos,  soap- 
stone  and  chrome  iron,  as  well  as  to  the  precious 
metals,  and  in  sandstone  and  shale  regions  the  out- 
look should  be  kept  for  coal,  fire  clays,  iron,  rock  salt 
and  gypsum.  In  a  coal  belt  it  is  almost  useless  to 
expect  mineral  veins,  for  apparently  no  fissures  made 
through  a  coal  bed  carry  ore  in  the  rocks  above  the 
coal,  whatever  they  may  do  below.  Any  one  who  will 
take  the  trouble  to  put  down  the  mineraroccurrences 
in  any  extended  region  will  soon  discover  that  they 
resolve  themselves  into  a  series  of  belts  corresponding 
with  the  rock  formation  of  the  country,  indicating 
most  unmistakably  the  little  understood  relation  be- 
tween them.  In  the  large  basaltic  areas  but  little  of 
interest  or  value  need  be  expected,  except  such  min- 
erals as  opal,  etc. ;  nor  is  it  any  use  to  search  for  the 
soluble  minerals,  such  as  saltpeter,  in  any  but  exces- 
sively hot  regions  of  depression,  without  drainage  out- 
lets, and  surrounded  by  volcanic  or  eruptive  rocks. 

Where  to  Search. — Above  all  things  the  prospec- 
tor's search  should  first  be  through  all  the  accessible 
regions  of  a  mineral  country,  for  in  such  districts  a 
much  smaller  ore  body  and  a  much  lower  grade  of  ore 
may  be  more  valuable  financially  than  greater  size 


PROSPECTING.  165 

and  richness  in  less  accessible  localities  amid  moun- 
tain fastnesses  and  eternal  snows.  It  is  time  to  enter 
these  when  all  others  are  exhausted,  though  their  fas- 
cination is  so  extreme  that  it  is  to  them  that  the  hope- 
ful adventurer  first  directs  his  footsteps. 

Prime  Requisites. — What  is  wanted  by  the  capi- 
talist is  a  large  ore  body,  fair  average  quality,  good 
working  facilities  and  reasonably  easy  access.  Given 
these,  there  is  usually  no  difficulty  in  securing  all  the 
capital  necessary.  The  want  of  any  of  these  qualities 
in  the  mine  renders  the  task  more  difficult. 

Outfit. — The  extent  of  equipment  will  vary  accord- 
ing to  the  character  of  the  country  to  be  traversed, 
the  distance  from  supply  points,  and  whether  the 
prospector  has  any  means  of  conveyance,  such  as  a 
pack  horse  or  burro,  or  has  to  carry  everything  him- 
self. It  is  unnecessary  to  speak  here  of  clothing, 
blankets,  food,  etc.,  further  than  to  say  that  the  lined 
and  riveted  canvas  suits  are  perhaps  the  most  service- 
able, and  that  comfortable  as  well  as  strong  boots  are 
an  important  item. 

Among  the  details  of  equipment  the  following  may 
be  mentioned.  The  horn  spoon  is  preferable  to  the 
gold  pan  or.  batea  for  prospecting,  as  being  more  con- 
venient to  carry  (it  can  go  in  a  pocket)  and  in  use 
requires  very  little  water,  and  does  not  fatigue  the 
user  by  causing  prolonged  stooping.  A  small  bottle 
of  quicksilver  will  be  found  useful  when  testing  for 
gold  in  a  very  fine  state.  A  compass  with  folding 
sights  and  a3-in.  needle  will  help  in  laying  off  ground 
and  connecting  a  location  with  other  monuments  or 
landmarks.  A  tape  is  not  necessary,  as  one  can  be 
improvised  from  well  stretched  linen  cord,  standard- 
ized by  some  measure  before  starting  and  knotted  at  1 
ft.,  1  yd.,  10  yds.  and  50  ft.  long.  If  a  regular  tape 
is  taken  that  with  steel  wire  interwoven  is  preferable  to 
a  heavy  steel  tape,  or  a  small  self-winding  narrow 
steel  tape  can  be  had,  which  occupies  less  than  the 
space  of  a  watch.  A  small  bar  magnet  is  useful  in 


166         PROSPECTING-  AND   VALUING  MINES. 

cleaning  up  pannings.  In  this  connection  it  may  be 
noted  that  in  the  absence  of  a  regular  gold  pan  very 
good  results  can  be  obtained  with  almost  any  sort  of  a 
receptacle,  such  as  a  frying  pan,  tin  dish,  etc.  For 
testing  sulphurets  and  dark  minerals  generally  a  white 
surface  is  preferable,  such  as  that  of  a  sancer  or  small 
bowl,  in  using  which  when  taking  samples  from  a  wet- 
crushing  battery  care  must  be  taken  to  avoid  overflow 
and  consequent  concentration  if  quantitative  results 
are  wanted.  When  sampling  placer  ground  two 
buckets  are  very  handy,  to  be  used  by  washing  from 
one  to  the  other.  To  examine  ores,  float,  pan  or  horn 
residues  and  rock  minerals  a  lens  is  almost  indispens- 
able, and  the  small  powerful  Coddington  style  is  per- 
haps best.  It  can  be  hung  to  the  watch  guard. 

Every  prospector  ought  to  have  some  knowledge  of 
the  use  of  the  blowpipe  in  determining  ores  and  min- 
erals and  making  rough  quantitative  assays.  The 
whole  blowpipe  kit  necessary  can  go  in  the  smallest 
size  cigar  box.  The  cheap  black  blowpipe  answers  as 
well  as  an  expensive  platinum-tipped  one,  and  a  tallow 
candle  is  for  most  purposes  better  than  the  alcohol  or 
oil  lamp.  The  half-dozen  reagents  suggest  themselves. 
A  small  streak  plate  should  be  included  in  the  kit. 

As  to  tools,  the  selection  will  depend  upon  means 
of  carriage  and  whether  any  real  opening  work  is 
intended.  In  prospecting  in  a  bare,  rocky  counti'3r 
where  no  digging  is  required,  a  light  poll  pick,  with 
say  a  3-lb.  head  or  even  lighter,  is  generally  suffi- 
cient, as  this  tool  combines  pick  with  hammer. 
Regular  geological  hammers  of  peculiar  shape  and 
special  steel  can  be  bought  or  made  by  any  good 
blacksmith,  but  are  rather  ornamental  than  necessary. 
Of  course  if  there  are  two  or  more  in  the  party  each 
should  take  a  different  tool.  If  there  is  a  pack 
animal,  then  a  light  working  pick  and  small  short- 
handled  shovel  will  be  taken. 

However,  as  to  all  these  matters  prospectors  of  any 
experience  do  not  need  to  be  told  what  is  necessary, 


CHAPTER  X. 
MAKING  LOCATIONS, 

The  object  of  making  a  location  on  a  piece  of  min- 
eral ground  is,  in  the  first  place,  to  give  notice  to  all 
other  persons  that  the  locator  has  found  mineral 
therein,  and  has  made  a  claim  to  a  definite  portion  of 
the  deposit  and  a  definite  amount  of  ground  to  work 
it  to  the  best  advantage.  To  secure  this  object  he 
posts  on  the  mineral  deposit  a  notice  of  his  claim,  to 
be  filed  for  record  with  the  proper  authorities  at  a 
later  date;  and  erects  such  monuments  as  will  define 
the  limits  of  the  ground  claimed.  This  notice  and 
the  monuments  secure  to  the  locator  a  possessory  title, 
which  is  good  so  long  as  the  requirements  of  the 
United  States  government,  and  the  local  laws  of  the 
particular  mining  district  in  which  the  claim  is 
located,  in  regard  to  the  amount  of  work  to  be  done  on 
the  claim  annually  and  other  conditions,  are  complied 
with.  The  ultimate  object  of  making  a  location  is  to 
secure  a  patent  to  the  ground  from  the  United  States, 
if  the  property  prove  to  be  worth  the  expense. 

What  is  said  here  applied  to  the  public  domain  of 
the  United  States,  in  the  far  West.  In  the  Eastern 
States  and  in  foreign  countries  the  practice  is  differ- 
ent, and  local  regulations  must  be  studied. 

The  basis  of  all  proceedings  to  acquire  patent  to 
mineral  ground  (see  Chap.  XI)  is  a  duly  certified  copy 
of  the  notice  of  location  and  the  monuments  which  it 
describes. 


168         PROSPECTING  AND   VALUING  MINES. 

Government  Requirements. — The  instructions  is- 
sued to  the  deputy  mineral  surveyors,  to  whom  the 
work  of  making  surveys  for  patent  is  intrusted,  are  of 
the  most  stringent  character.  "Under  these  instruc- 
tions, the  surveyor  has  to  report  the  true  position  of 
all  the  original  monuments,  or  give  good  reason  for 
their  absence,  which  will  be  acceptable  to  the  exami- 
ners of  the  United  States  land  office  at  Washington; 
he  must  make  the  end  lines  of  the  claim  parallel  (if  it 
be  a  lode  claim);  and  he  must  not  include  within  the 
exterior  lines  of  the  survey  any  ground  outside  the 
corner  monuments.  Whether  this  always  does  justice 
to  the  locator  is  not  the  question;  it  is  the  ruling  of 
the  department  and  must  be  respected.  Neglect  to 
restore  monuments  in  the  spring  which  may  have  been 
destroyed  by  winter  storms,  may  result  in  litigation 
and  endless  delay  in  securing  title,  as  their  presence  is 
the  only  thing  which  will  debar  a  second  party  from 
coming  on  the  ground  and  making  an  adverse  loca- 
tion. It  is  taken  for  granted  that  a  person  making  a 
location  will  look  for  monuments  as  a  sign  of  previous 
appropriation  of  the  ground,  and  their  absence  justi- 
fies the  supposition  that  the  ground  is  vacant  and 
locatable,  or  if  previously  located  has  been  abandoned 
by  the  earlier  claimants.  A  locator  cannot  plead  igno- 
rance of  the  absence  of  his  monuments,  because  as 
they  are  the  sole  witnesses  of  the  limits  of  his  claim, 
and  the  essential  means  by  which  he  holds  possession, 
it  is  his  duty  as  well  as  his  interest  to  see  that  they 
are  maintained  in  good  order. 

Imperfect  Locations.  --  The  number  of  locations 
which  satisfactorily  fill  the  requirements — that  is, 
which  have  all  the  monuments  standing  and  so  located 
that  upon  survey  they  will  not  exclude  some  portion  of 
ground  to  which  the  claimant  feels  that  he  is  honestly 
entitled,  because  the  location  was  made  and  held  in 
good  faith — is  exceedingly  small.  The  majority  of 
original  locations  are  very  imperfectly  made;  not  from 


MAKING  LOCATIONS.  169 

lack  of  good  intentions  on  the  part  of  the  locator,  but 
from  want  of  knowledge  as  to  what  is  required,  or 
how  to  do  it,  or  the  lack  of  proper  instruments.  As  at 
present  interpreted,  the  instructions  issued  to  the 
deputy  surveyors  really  call  for  nearly  as  great  accu- 
racy on  the  part  of  the  prospector  when  making  his 
location  as  they  do  from  the  deputy  when  making  the 
final  survey. 

Theoretically  the  regulations  are  based  on  the  idea 
that  in  parting  with  the  absolute  title  to  the  mineral 
lands  (which  until  a  comparatively  recent  period  were 
regarded  as  the  inalienable  property  of  the  crown)  the 
government  is  doing  so  on  such  extraordinarily  low 
and  favorable  terms  that  it  has  the  right  to  demand 
from  the  recipient  of  its  bounty  what  it  considers  to 
be  nothing  more  than  a  very  moderate  expenditure  of 
time  and  money  in  return  for  its  liberality.  If  the 
original  location  has  been  carefully  made,  and  the 
monuments  equally  carefully  maintained,  the  appli- 
cant for  patent  will  have  no  difficulties  or  delay  in  the 
land  office  proceedings,  as  90%  or  over  of  all  such 
troubles  arise  from  defective  locations  or  the  absence 
of  monuments  which  the  government  claims  should  be 
in  existence.  A  large  proportion  of  the  remainder  are 
dela3red  by  the  imperfect  character  of  the  work  on 
which  the  right  to  patent  is  based. 

There  seems  to  be  a  popular  idea  that  it  is  within 
the  scope  of  the  authority  of  the  deputy  surveyor  to 
restore  such  monuments  as  are  missing,  at  the  distance 
called  for  by  the  notice  of  location  instead  of  in  their 
original  position,  and  not  infrequently  an  implied 
feeling  that  he  ought  to  do  so  because  he  had  been 
favored  by  selection  to  do  the  work,  and  most  deputy 
surveyors  can  testify  to  the  difficulties  which  arise 
from  this  source,  between  the  applicant  for  survey  and 
the  officers  of  the  government,  in  which  the  deputy 
receives  no  support  from  the  government  and  is  very 
likely  to  secure  the  displeasure,  if  nothing  more  of 
the  applicant. 


170         PROSPECTING  AND   VALUING  MINES. 

WHAT  CAN  BE  LOCATED  AND  IN  WHAT  MANNER. — - 
Knowing  then  what  is  required  by  the  government,  let 
us  proceed  to  make  a  good  valid  location,  or  rather 
see  what  is  necessary  to  make  it  good,  first  stating  that 
the  extra  time  necessary  to  convert  a  defective  loca- 
tion into  a  good  one  is  so  small  as  to  be  of  no  conse- 
quence when  compared  with  the  subsequent  saving  of 
time,  money,  and  annoyance;  remembering  that  if  the 
ground  is  worth  locating  at  all  it  is  worth  while  to 
make  the  location  absolutely  secure. 

Mineral  Must  be  Found. — No  valid  location  can  be 
made  until  mineral  has  been  found  within  the  limits 
of  the  claim  in  the  condition  required  by  the  charac- 
ter of  the  location  made. 

Placer  locations  may  be  made  on  ground  in  which 
valuable  minerals,  such  as  gold,  tin,  platinum,  iridos- 
mine,  etc.,  are  mixed  with  sand,  gravel,  clay  or  bowl- 
ders, the  minerals  having  been  removed  by  natural 
causes  from  their  original  position  in  the  rock  in 
place.  Placer  ground  on  unsurveyed  land  may  be 
taken  in  any  shape  which  the  locator  desires,  provided 
the  ground  contains  mineral  as  described,  and  pro- 
vided the  area  does  not  exceed  20  acres  to  each  locator 
or  160  acres  to  an  incorporation.  But  if  the  land  has 
been  surveyed  by  the  government,  the  claims  must  be 
made  to  conform  to  the  smallest  legal  subdivisions 
(which  in  this  case  is  10  acres),  the  limits  of  the  placer 
ground  being  first  determined,  and  then  so  adjusted 
on  the  margins  of  the  location  that  10-acre  tracts  hav- 
ing less  than  five  acres  of  placer  ground  are  excluded, 
and  those  having  more  than  five  acres  of  available 
ground  are  included.  When  the  final  survey  for 
patent  is  made  on  unsurveyed  land,  it  will  be  made  to 
conform  to  the  original  takes  or  monuments,  no  matter 
how  irregular  the  shape  of  the  track  may  be,  regard- 
less of  anything  except  area,  and  this,  if  in  excess, 
must  be  cut  down  to  the  limit  allowed  by  law.  When 
the  ordinary  land  surveys  are  extended  over  such 


MAKING  LOCATIONS.  171 

areas  the  section  lines  are  adjusted  to  such  surveys, 
just  as  in  the  case  of  lode  claims. 

Lode  Locations. — In  the  location  of  mineral  veins 
or  lodes,  whether  they  be  of  gold,  silver,  copper,  lead, 
iron,  tin,  quicksilver  or -other  minerals  found  in  lodes, 
the  United  States  laws  grant  to  each  locator  the  right 
to  take  in  one  location  not  more  than  1,500  ft.  in 
length  on  the  lode,  and  not  more  than  300  ft.  on  each 
side  of  the  center  of  the  lode.  A  location  cannot  be 
made  with  200  ft.  on  one  side  and  400  ft.  on  the  other. 
There  is  nothing  compelling  the  locator  to  mats  his 
location  600  ft.  wide,  the  law  simply  says  he  may  so 
make  it. 

Local  Regulations. — Within  these  limits  the  width 
is  optional  with  the  locator,  and  by  the  action  of  a 
duly  organized  meeting  of  the  miners  in  any  district, 
may  be  limited  to  any  quantity  not  less  than  25  ft.  on 
each  side  of  the  center  of  the  lode,  making  a  total 
width  of  only  50,  instead  of  600  ft.  In  Bodie,  Cal., 
for  instance,  the  width  was  fixed  at  100  ft.  on  each 
side  of  the  center  line. 

The  local  laws  of  a  mining  district  may  impose  any 
other  conditions  which  the  miners  may  see  fit,  pro- 
vided they  do  not  grant  better  terms  than  are  offered 
by  the  government.  These  may  be  just  as  much  more 
stringent  as  the  miners  may  think  desirable  for  the 
welfare  of  the  district,  as,  for  instance,  while  the  United 
States  laws  have  been  construed  to  grant  the  locator 
one  year  from  the  first  day  of  January  succeeding  the 
date  of  his  location  in  which  to  do  the  $100  worth  of 
work  by  which  he  holds  his  title,  the  district  laws  may 
decide  that  work  shall  be  commenced  inside  of  60  or 
any  other  number  of  days,  or  stipulate  for  other  evi- 
dences of  good  faith  on  the  part  of  the  locator;  but 
they  cannot  legally  declare,  as  is  sometimes  attempted 
to  be  done,  that  a  shaft  10  ft.  deep,  which  only  cost 
$50,  shall  be  considered  full  value  for  the  required 
annual  expenditure  of  $100.  Such  a  proposition  is 


172         PROSPECTING  AND  VALUING  MINES. 

always  open  to  contest.  As  the  want  of  roads  often 
greatly  retards  the  opening  of  otherwise  promising 
mining  camps,  a  clause  might  very  suitably  be  added 
to  many  local  laws,  stipulating  that  each  location  pay 
annually  a  definite  sum  to  some  authorized  agent  to 
accumulate  as  a  road  fund,  in  addition  to  the  $100 
work  required  by  the  government,  but  such  payment 
could  not  be  made  to  constitute  a  portion  of  the 
annual  assessment  work. 

Mineral  "in  Place." — As  previously  stated,  no  loca- 
tion «can  be  made  which  will  be  of  any  value  until 
mineral  has  actually  been  found,  and  for  a  lode  loca- 
tion it  must  be  in  the  undisturbed  rock,  or  "rc-^k  in 
place."  Monuments  or  no  monuments,  any  outsider 
can  prospect  over  such  a  lode  location,  and  if  h**  suc- 
ceeds in  finding  mineral  in  place  before  the  earlier 
claimant,  he  can  make  an  adverse  location  ana  will 
surely  hold  the  ground.  In  Leadville,  for  instance, 
where  the  ore  did  not  crop  on  the  surface  (uring 
nearly  horizontally),  the  ground  was  covered  with 
overlapping  locations,  but  the  shaft  which  first  got 
down  to  and  struck  the  deposit  took  the  ground  as 
against  the  other  claimants. 

Agricultural  and  Timber  Eights. — No  mining  loca- 
tion, either  lode  or  placer,  or  for  iron  or  for  coa-,  can 
be  made  on  any  ground  for  which  a  patent  has  been 
issued,  unless  it  can  be  conclusively  proved  thf»fc  the 
party  obtaining  such  patent  was  aware  of  the  existence 
of  mineral  on  his  claim  at  the  time  of  " proving  up" 
and  falsely  swore  to  the  contrary.  This  applies  to 
patents  to  agricultural  and  timber  lands.  A  lode  claim 
can  be  filed  over  a  placer  claim,  as  lodes  are  expressly 
exempted  from  placer  patents,  but  across  such  placer 
claim, the  lode  camp  has  surface  ground  only  25  ft.  on 
each  side  of  the  center  of  the  lode. 

Locations  can  be  made  on  all  other  classes  of  land, 
provided  mineral  has  been  found  thereon ;  but  when 
made  on  land  valuable  for  timber  or  agricultural  pur- 


MA  KING  LOG  A  TIONS.  173 

poses,  are  liable  to  contests  before  the  land  office  to 
determine  whether  the  ground  is  more  valuable  for 
mineral  or  for  other  purposes. 

Monuments. — A  monument  should  be  conspicuous 
enough  to  be  readily  found.  According  to  the  char- 
acter of  the  region,  it  may  be  either  a  tree  with  the 
side  blazed;  a  small  sapling  cut  off  about  4  ft.  from 
the  ground  with  the  top  squared  ;  a  simple  stake  about 
4  ft.  long  squared  at  the  top,  and  driven  not  less  than 
12  in.  in  the  ground,  if  there  are  no  rocks  convenient; 
or  such  a  stake  with  a  rock  mound  at  its  base;  or  even 
a  simple  pile  of  rocks  where  there  are  no  trees. 

Tree  or  Stake  Marks. — In  all  cases  where  a  tree  or 
stake  is  used  a  sufficient  space  should  be  smoothed  on 
which  to  write  the  designation  of  the  corner  intended 
to  be  represented.  If  a  tree  is  used,  it  is  not  suffi- 
cient to  simply  bark  it,  because  trees  in  falling  often 
skin  the  bark  off  each  other  in  patches,  and  such  a 
"blaze"  is  easily  overlooked;  but  the  blaze  should  be 
made  as  in  pi.  15,  figs.  1  and  2,  with  a  straight  notch 
at  the  bottom,  cut  well  into  the  wood  and  dressed 
smooth  to  wrrte  on  with  a  soft  pencil.  Fig.  1  shows 
the  front  view  of  a  proper  blaze  and  fig.  2  the  side  ap- 
pearance. Such  a  mark  is  unmistakable  and  immedi- 
ately suggests  the  prior  presence  of  men,  which  the 
other  method  does  not. 

Stone  and  stake  monuments  are  easily  overturned 
and  destroyed,  especially  in  snowy  altitudes  and  on 
steep  hillsides,  but  there  would  not  be  half  as  much 
trouble  in  keeping  them  in  good  shape  if  a  little  more 
care  were  exercised  in  building  them.  They  are 
usually  a  heap  of  rocks,  instead  of  a  monument.  It 
takes  no  more  rocks  to  build  a  good  than  a  bad  one, 
and  but  little  if  any  more  time — all  depends  on  the 
manner  of  placing  the  stones.  If  the  monument  is  to 
contain  a  stake,  this  should  be  driven  solid,  with  a 
rock  for  a  hammer  if  necessary,  and  the  ground 
roughly  leveled  off  with  the  pick,  which  the  prospector 


174        PROSPECTING  AND  VALUING  MINES, 

always  carries,  so  as  to  get  a  good  foundation.  This 
is  all  important  on  a  hillside.  The  necessary  supply 
of  rocks  should  then  be  got  together,  before  starting 
the  structure.  The  biggest  and  flattest  should  be  laid 
in  a  circle  round  the  stake,  at  a  little  distance  from  it, 
in  such  a  way  that  their  upper  surfaces  slope  inward 
toward  the  stake.  By  taking  this  precaution  with  the 
bottom  layer,  the  next  layer  will  have  a  tendency  to 
slide  in  toward  the  stake,  thus  making  it  almost  im- 
possible for  the  monument  to  tumble  down,  while  the 
stake  will  be  wedged  tightly  in  place  by  the  pressure ; 
and  if  this  principle  is  applied  until  the  monument  is 
completed,  say  three  courses,  with  the  inner  space 
filled  up  solid  with  small  rocks  and  dirt,  there  need  be 
no  fear  of  its  destruction,  except  willfully  or  by  snow- 
slides  sweeping  everything  before  them.  If  the  latter 
are  feared  it  is  best  not  to  have  the  central  post  too 
high,  as  it  will  then  offer  less  resistance  to  the  over- 
turning action  of  the  snow.  PI.  15,  figs.  3  and  4, 
show  a  properly  and  an  improperljr  built  monument  in 
cross  section.  In  the  latter  there  is  every  chance  for 
the  monument  to  fall  apart  and  release  the  stake  from 
its  position.  Every  stone  in  a  monument  should  be 
moved  about  until  it  has  a  perfectly  solid  bearing,  and 
does  not  wobble. 

Simple  Eock  Monuments. — In  building  a  monument 
of  rocks  alone,  the  importance  of  a  good  foundation  is 
even  greater,  for  the  absence  of  the  central  stake  in- 
creases the  liability  to  destruction.  A  moderately 
large  base  tapering  somewhat  rapidly  will  give  the 
greatest  stability. 

Inspection  of  Monuments. — To  emphasize  the  im- 
portance of  building  well,  it  will  not  be  out  of  place 
to  repeat  that  the  owner  of  an  unpatented  claim  should 
at  least  annually  examine  the  corner  monuments,  and 
see  that  they  are  standing,  for  as  they  are  often  the 
only  means  by  which  a  stranger  can  have  knowledge 
of  the  existence  of  a  location  or  its  extent,  and  their 


MAKING  LOCATIONS.  175 

object,  is  to  give  notice  to  the  world  of  an  existing 
claim,  their  absence  gives  the  stranger  a  perfect  right 
to  locate  the  ground  as  vacant  lands  of  the  United 
States. 

Notices  of  Location. — These  should  accurately  de- 
scribe the  monuments  as  actually  set.  Prospectors 
frequently  take  out  a  set  of  printed  blanks  in  which  a 
"mound  of  stones"  is  usually  called  for,  and  then 
simply  fill  in  the  blank  spaces  with  the  number  of  feet 
located, when  it  often  happens  that  no  mound  of  stones 
was  made,  but  a  tree  blazed,  or  a  small  sapling  cut 
off,  in  places  where  there  is  a  scarcity  of  rocks  suita- 
ble for  a  monument.  Frequently  the  stake  called  for 
does  not  exist,  and  the  writer  has  seen  cases  where  the 
monument,  so  called,  was  nothing  more  than  a  small 
piece  of  a  broken  limb  stuck  in  the  ground,  without 
any  notice  of  what  it  was  intended  to  represent,  and 
absolutely  not  recognizable  as  a  monument,  and  this 
in  the  midst  of  dense  timber.  Such  negligence  is 
inexcusable,  and  if  trouble  arises  the  locator  has  no 
one  but  himself  to  blame.  It  is,  of  course,  allowable 
to  use  one  of  these  printed  blanks  to  make  and  post 
the  original  notice  at  the  point  of  discovery,  to  hold 
the  claim  while  the  discoverer  may  be  putting  up  his 
end  and  corner  monuments,  but  the  final  notice,  of 
which  a  copy  is  filed  for  record,  should  call  for  a 
blazed  tree,  describing  its  markings,  if  such  were 
used,  a  sapling  squared,  a  post  without  mound,  a  post 
with  rock  mound,  or  a  rock  mound  only,  as  the  case 
may  be.  t  Occasionally  the  notice  of  location  calls  for 
a  monument  of  some  kind,  in  a  position  which  is  inac- 
cessible, and  where  none  was  actually  set,  so  that 
when  the  deputy  surveyor  comes  along  and  reports 
that  he  cannot  reach  the  point  called  for,  there  imme- 
diately arises  a  question  of  veracity  between  the  loca- 
tor and  the  deputy,  which  may  seriously  delay  the 
proceedings  in  the  land  office.  If  the  point  where  the 
monument  should  be  set  is  inaccessible,  the  location 


176        PROSPECTING  AND  VALUING  MINES. 

notice  should  say  so,  and  give  the  reason  for  not  set- 
ting the  corner,  and  if  set  as  a  witness  post  to  show 
the  direction  of  the  end  line,  the  supposed  distance  to 
the  corner  should  be  written  thereon.  The  absence  of 
a  post  at  any  of  the  corners,  if  such  cannot  be  set, 
does  not  invalidate  a  location,  if  the  fact  be  so  stated, 
as  the  law  does  not  ask  impossibilities,  but  the  state- 
ment that  a  corner  was  set  in  an  inaccessible  place, 
when  it  was  not  so  set,  is  sure  to  result  in  trouble. 

Posting  Notices. — In  addition  to  fully  describing 
the  monuments  in  the  notice  of  location,  they  should 
be  so  marked  as  to  indicate  what  position  they  occupy 
with  reference  to  the  claim,  as  "north  end  center  of 
Deadwood  lode,"  "northwest  corner  of  Dead  wood 
lode"  etc. ;  but  if  a  stone  monument  be  used  the 
notice  may  be  folded  up  and  placed  between  two  flat 
stones  or  in  a  tin  can,  with  the  mouth  downward  to 
keep  it  dry.  Such  a  tin  can  is  also  very  useful  even 
when  a  post  is  used,  as  it  can  be  tacked  to  the  same 
(pi.  15,  fig.  5)  in  a  similar  manner  and  forms  a  very 
noticeable  and  conspicuous  object.  If  there  are  trees 
near  the  monuments,  they  should  also  be  blazed  and 
marked  as  witness  trees. 

The  notice  should  distinctly  state  the  name  of  the 
state,  county  and  mining  district  in  which  it  is  made, 
the  name  of  the  miner,  the  name  of  the  adjacent 
claims  if  they  are  known,  the  date  of  discovery,  the 
date  of  location,  with  witnesses  if  possible,  and  refer- 
ence should  be  made  to  prominent  natural  objects,  so 
as  to  make  the  position  of  the  claim  ascertainable,  if, 
after  all  precautions  have  been  taken,  the  monuments 
should  be  accidentally  destroyed,  as  by  floods  or 
snowslides.  Such  references  may  be,  for  instance, 
"on  south  side  of  Index  Mountain,"  "on  the  north 
side  of  Crab  Creek,  2  miles  above  its  junction  with 
Pole  Creek,"  "2  miles  northeast  of  Minersville,"  etc. 

The  exact  wording  of  the  notice  of  location  is  of  but 
little  consequence,  so  long  as  it  gives  the  information 


MAKING  LOCATIONS.  177 

previously  stated,  as  a  location  of  lode  claim  neces- 
sarily carries  with  it  all  the  dips,  spurs  and  angles, 
and  all  the  privileges  granted  by  the  various  acts  of 
Congress,  without  a  recital  of  such  claims.  All  that  is 
required  is  such  a  document  that  no  one  can  misun- 
derstand the  intention  of  the  locator.  If  this  is 
clearly  done,  the  shorter  the  notice  the  better. 

It  has  taken  some  time  to  describe  the  requisites  of 
a  first-class  notice  of  location,  whereas  it  only  takes  a 
few  minutes  to  write  it  out  and  secure  the  satisfaction 
which  always  goes  with  a  job  well  done,  but  it  is  not 
intended  to  imply  that  a  notice  not  so  complete  as 
here  sketched  would  be  invalid.  But  very  few  con- 
tain every  item  in  detail,  yet  the  nearer  it  approaches 
to  the  correct  thing  the  more  safely  can  the  prospector 
leave  his  claim  to  the  tender  mercies  of  the  elements. 

How  TO  MAKE  A  LOCATION. — Placer  and  Coal. — In 
making  a  location  of  placer  or  coal  ground  on  surveyed 
land  the  location  notice  should  describe  the  ground 
by  the  usual  legal  subdivisions,  and  this  will  consti- 
tute a  valid  description  because  it  can  be  immediately 
filed  in  the  United  States  land  office  and  become  the 
best  public  notice  obtainable;  but  if  the  placer  claim 
is  on  unsurveyed  land,  a  monument  must  be  set  at 
every  change  in  the  direction  of  the  exterior  bound- 
aries and  mentioned  in  the  location  notice.  Coal 
lands  can  only  be  taken  in  legal  subdivisions  as  platted 
on  the  ordinary  land  surveys,  and  cannot  be  pur- 
chased before  survey  of  the  township  has  been  made. 

Lodes. — In  the  case  of  lode  claims  it  is  customary 
to  set  the  ends  of  the  lode  line  and  the  four  corners  of 
the  claim,  but  there  have  been  decisions  by  the  gen- 
eral land  office  in  which,  with  only  the  end  center 
stakes  established,  the  locations  were  sustained.  If 
this  method  be  employed  the  discovery  stake,  as  well 
as  the  monuments  at  the  ends  of  the  claim,  should  be 
most  thoroughly  established,  and  all  of  them  should 
plainly  show  that  the  locator  claims  a  definitely  speci- 


178         PROSPECTING  AND   VALUING  MINES. 

fied  distance  on  each  side  of  his  lode  line.  Such  de- 
cisions are  based  on  the  theory  that  the  surface 
ground  is  granted  only  to  enable  the  miner  to  work 
his  claim  to  the  best  advantage,  and  on  the  further 
idea  that  a  person  finding  a  lode  will  naturally  follow 
the  outcrop  in  the  course  of  his  examination,  and 
must  consequently  find  any  monuments  already 
erected  on  the  vein,  thus  gaining  knowledge  of  the 
claims  of  any  prior  locators.  But  this  would  not 
occur  if  the  locator  were  following  a  lode  parallel  to 
one  previously  located  and  say,  therefrom,  so  that  it  is 
very  much  safer  to  establish  all  the  corner  monuments, 
this  method  having  the  additional  advantage  of  defin- 
ing the  direction  of  the  end  lines,  which  is  left  open 
to  interpretation  in  the  other  case,  unless  it  is  plainly 
stated  that  they  are  to  be  at  right  angles  to  the  lode 
line.  The  following  remarks  will  therefore  apply  only 
to  claims  having  all  corners  established,  except  where 
they  are  evidently  applicable  to  other  locations  also. 

It  may  seem  a  very  simple  matter  to  make  a  lode 
location  after  finding  ore — just  measure  off  1,500  ft. 
and  set  the  corner  posts — but  there  are  many  points 
to  be  considered,  if  we  want  to  secure  the  full  privi- 
leges granted  by  the  mining  laws.  Should  there  be 
any  mistake  in  the  form  or  direction  of  the  original 
location,  and  adjacent  claims  be  taken  either  endwise 
or  laterally  before  the  mistake  is  discovered,  it  will  be 
too  late  to  remedy  the  defect  by  a  new  location;  as, 
for  instance;  if  the  direction  of  the  lode  line  as 
located  does  not  follow  the  lode,  which  may  be  found 
to  run  diagonally  across  the  location,  and  pass  out  of 
the  side  instead  of  the  end  lines.  In  such  a  case  the 
side  lines  become  the  end  lines,  making  the.  location  on 
the  lode  much  shorter  than  if  the  lode  ran  lengthwise 
of  the  claim.  To  avoid  such  errors,  which  may  ruin 
an  otherwise  valuable  mine,  time  enough  should  be 
taken  to  ascertain  the  true  direction  of  the  vein  before 
measuring  off  the  location,  After  establishing  the 


MAKING  LOCATIONS.  1?9 

initial  monument  or  discovery  stake  on  the  ore  body, 
and  posting  a  notice  of  location  thereon,  so  that  there 
can  be  no  doubt  as  to  what  vein  is  intended  to  be 
located,  the  prospector  is  entitled  to  a  reasonable  time 
in  which  to  perfect  his  location. 

Very  often  the  notice  of  location  is  posted  at  one 
end  of  the  claim  (see  A9  pi.  15,  fig.  10)  and  calls  for 
"  1,500  ft.  on  this  vein,  beginning  at  the  post  on 
which  this  notice  is  posted,"  or  similar  language, 
when  there  is  no  vein  in  sight  at  that  particular  point, 
leaving  the  intention  of  the  locator  uncertain,  or  to  be 
interpreted  only  by  finding  the  monument  at  the  other 
end  of  the  location,  and  ascertaining  what  outcrop 
may  fall  on  a  line  drawn  between  the  two  monuments, 
which  may  or  may  not  be  the  vein  intended.  As  in 
pi.  15,  fig.  11,  if  the  notice  be  posted  at  either  end  of 
the  lode  line  1  or  2,  a  line  connecting  these  points 
may  show  the  outcrop  of  ore  to  be  say  150  ft.  from  the 
line,  in  which  case,  in  strict  compliance  with  the  law, 
in  final  survey  for  patent,  the  line  from  5  to  6  should 
be  run  through  the  point  7,  making  the  distance  from 
7  to  the  center  of  the  outcrop  not  more  than  300  ft. 
By  establishing  a  discovery  monument  all  doubt  is 
ended. 

Lode  Line  and  Outcrop. — It  is  not  absolutely  neces- 
sary that  the  location  should  be  made  in  a  straight 
line,  but  the  lode  line  should  follow  the  outcrop  with 
reasonable  accuracy.  This  is  often  a  very  crooked 
line  if  the  vein  has  a  flat  dip.  If  the  vein  is  largely 
quartz  and  therefore  generally  harder  than  the  sur- 
rounding country  rock,  it  will  probably  crop  boldly 
and  can  be  traced  without  difficulty.  If  softer  than 
the  inclosing  rocks,  it  may  only  crop  on  the  steep 
sides  of  ravines,  and  be  covered  on  the  gentler  slopes 
by  earth  and  debris,  in  which  case  it  may  be  necessary 
to  dig  a  few  cross  trenches  at  short  intervals  apart,  so 
as  to  disclose  its  course.  (See  Chap.  IX.,  for  method 
of  tracing  outcrop.)  "When  all  other  signs  fail  it  will 


180        PROSPECTING  AND  VAL  UIN9  MINES. 

probably  be  found  to  run  parallel  to  the  general  direc- 
tion of  other  veins  in  the  district,  or  else  nearly  at 
right  angles  thereto.  Jn  the  latter  case  it  may  prove 
to  be  only  a  spur  of  a  larger  vein,  as  shown  on  pi.  3, 
fig.  4,  E.  At  any  rate  a  notice  at  the  point  of  discov- 
ery will  hold  a  claim  for  a  few  days,  while  the  true 
position  of  the  end  lines  is  being  established,  and  with 
ordinary  diligence  and  a  little  woodcraft  the  direction 
of  the  lode  may  generally  be  determined  with  a  rea- 
sonable amount  of  accuracy,  if  the  principles  govern- 
ing the  outcrop  of  a  vein  have  been  mastered,  and  the 
vein  is  strong  enough  to  be  worth  locating. 

In  cases  where  the  vein  does  not  crop  distinctly  for 
1,500  ft.,  it  will  be  good  policy  to  make  two  locations, 
establishing  one  of  the  end  lines  of  each  location 
through  the  discovery  stake  on  the  outcrop  as  in  p). 
15,  fig.  9,  which  leaves  a  portion  of  the  cropping  on 
each  location,  A  and  B.  This  plan  has  the  advantage 
also  of  lessening  the  chance  of  the  rake  of  the  ore  body 
in  depth  carrying  it  beyond  the  end  lines  of  the  claim, 
and  offers  a  better  chance  to  develop  both  locations 
through  the  same  tunnel  or  shaft.  This  plan  is  much 
preferable  to  the  common  one  (pi.  15,  fig.  10)  of  cov- 
ering all  the  outcrop  by  the  location  A  and  making 
extension  locations  B  and  C,  in  which  no  outcrop  is 
visible,  as  the  latter  locations  are  invalid  until  ore  has 
been  found  in  them.  In  the  one  case  the  locator  has 
a  good  title  to  3,000  ft.  in  the  other  to  only  1,500. 

Length  and  Extensions. — Having  determined  the 
direction  of  the  lode  line,  and  the  manner  in  which  he 
will  make  his  locations,  the  locator  can  measure  out 
any  number  of  feet  in  either  direction  for  his  claim  or 
claims,  provided  the  total  length  of  each  one  does  not 
exceed  the  statutory  limit  of  1,500  ft.,  and  the  end 
monuments  may  be  established.  From  the  same  point 
he  can  take  one  claim  with  say  500ft.  in  one  direction 
and  1,000  ft.  in  the  other,  or  two  claims  of  1,500  ft. 
each,  one  in  each  direction  from  the  discovery.  If 


MAKING  LOCATIONS.  181 

only  one  claim  is  laid  off,  it  is  good  policy  to  be  sure 
that  the  location  is  fully  1,500  ft.  long;  if  a  little 
more  it  will  not  matter,  as  on  final  survey  the  claim 
can  be  cut  down  to  its  proper  length  if  in  excess,  but 
it  cannot  be  lengthened  beyond  the  original  stakes,  if 
they  have  been  established  too  close  together,  and  the 
claimant  may  lose  a  portion  of  ground  to  which  he 
might  have  been  legally  entitled.  If  on  the  other 
hand,  a  series  of  locations  are  made  on  the  same  vein, 
it  will  always  be  policy  to  make  the  locations  a  trifle 
less  than  1,500  ft.  each  in  length  (unless  measured 
with  the  accuracy  of  a  final  survey),  so  as  to  avoid 
awkward  gaps  between  them,  as  will  be  seen  must 
occur  in  such  a  series  as  shown  in  pi.  15,  fig.  6,  where 
it  is  evident  that  the  end  lines  of  location  A  must  be 
finally  established  at  1  and  2.  If  2  has  been  taken  as 
one  end  of  B,  the  other  must  be  set  20  ft.  short  of  the 
original  post  at  3,  or  at  4.  The  ends  of  D  can  be  set 
at  5  and  6,  but  if  5  be  taken  as  one  end  of  G  there  will 
be  a  gap  of  60  ft.  between  3  and  7,  making  a  total  of 
80  ft.  at  this  point  to  be  relocated,  and  secured  only 
by  an  expenditure  of  $500  for  labor,  in  addition  to  the 
cost  of  survey  and  land  office  proceedings.  Under 
other  circumstances  the  gap  of  20  ft.  may  occur  near 
2  and  60  ft.  near  5.  It  is  better  to  make  the  locations 
safe  from  this  defect  by  making  each  of  them  a  trifle 
short  and  making  an  additional  one,  if  necessary  to 
cover  all  the  ground  desired. 

Even  in  the  case  of  four  claims  of  rather  irregular 
length,  but  aggregating  just  6,000  ft.,  all  owned  by 
the  same  corporation,  the  laud  office  would  not  permit 
the  adjustment  cff  the  dividing  end  lines  to  make  four 
even  surveys  of  1,500  ft.  each,  but  requires  strict 
adherence  to  the  original  monuments. 

Setting  Corner  Monuments. — -In  setting  the  corner 
monuments,  be  sure  that  they  are>  if  anything,  a  little 
farther  from  the  lode  line  than  the  distance  called  for 
in  the  notice  of  location,  as  the  distance  allowed  on 


182         PROSPECTING  AND  VALUING 

final  survey  cannot  be  greater  than  the  position  of  the 
corner  monuments  calls  for;  in  other  words,  the 
monuments  govern  and  not  the  words  of  the  location 
notice.  No  ground  can  be  included  in  the  final  sur- 
vey for  patent  which  lies  outside  straight  lines  con- 
necting the  monuments  as  they  exist  on  the  ground^ 
and  the  end  lines  must  be  parallel. 

Having  taken  the  precaution  to  keep  the  corner 
monuments  far  enough  away  from  the  lode  line  so  that 
the  finally  established  side  lines  shall  fall  within 
them,  it  is  next  necessary  to  see  that  they  are  so 
located  that  the  end  lines  can  be  drawn  parallel  to 
each  other,  and  yet  pass  through  the  end  monuments 
on  the  lode  line.  It  is  here  that  the  deputy  surveyor 
usually  encounters  the  greatest  difficult}'.  The  situa- 
tion can  best  be  explained  by  such  a  diagram  as  pi. 
15,  fig.  7,  in  which  Z  shows  a  defective  location,  be- 
cause if  AB  represents  the  lode  line,  and  CJ),E,F,  the 
four  corner  monuments;  the  surveyor,  to  make  the  end 
lines  parallel,  must  prolong  EBm  toward  F  as  in  the 
dotted  line,  and  then  from  C  lay  off  a  parallel  line 
toward  D  thus  cutting  the  lode  line  short  by  the  dis- 
tance A  H.  He  cannot  draw  the  end  line  SS  through 
A,  because  it  would  include  ground  outside  the  posts 
or  monuments,  namely  the  triangles  S,D,A  and  S,C,A 
not  included  in  the  original  location.  In  the  same 
figure  W  shows  a  well-made  location,  so  far  as  the 
prospector's  interests  are  concerned,  as  it  is  evident 
that  the  end  lines  SS  and  00  can  be  drawn  through 
the  lode  line  posts  A  and  J",  without  shortening  the 
length  of  the  lode  line,  and  can  have  a  variety  of  di- 
rections given  to  them,  while  remaining  parallel,  a 
point  of  great  importance,  as  will  be  seen  shortly. 

It  follows  almost  inevitably  that  one  satisfactory  loca- 
tion must  in  common  practice  necessitate  an  adjacent 
location  in  bad  shape,  so  that  whatever  may  be  said  of 
the  policy  of  making  the  lode  line  monuments  of  one 
location  common  to  its  extensions,  the  ordinary  prac- 


MAKING  LOCATIONS.  183 

tice  of  making  the  corner  monuments  also  common  to 
adjacent  claims  should  be  abandoned  by  those  who 
wish  to  avoid  trouble  on  final  survey.  Independent 
posts  should  be  established  as  shown  on  pi.  15,  fig.  8. 
In  this  figure  the  corner  monuments  of  location  A  are 
marked  a3a*a5a6,  while  its  corners  of  location  B  are 
numbered  63,6*,fr5,  and  66.  The  diagram  explains 
itself,  being  only  two  locations  like  W  in  fig.  7,  placed 
end  to  end.  By  adopting  this  system,  the  parallel  end 
lines  can  be  located  anywhere  in  the  ground  covered 
by  the  overlapping  corners,  as  shown  by  the  heavy 
parallel  cross  lines. 

End  Lines. — The  acts  of  Congress  grant  to  the 
locator  1,500  linear  feet  on  the  vein,  and  call  for  par- 
allel end  lines,  so  that  a  uniform  length  on  the  vein 
shall  be  maintained  at  all  depths,  as  the  miners  follow 
the  vein  downward  on  its  dip,  the  end  lines  being  ex- 
tended downward  vertically  and  prolonged  indefinitely 
in  the  direction  of  the  dip.  If  any  other  policy  were 
allowed,  the  ownership  on  the  vein  in  depth  would 
be  a  variable  quantity,  diminishing  in  length  if  the 
end  lines  of  the  claim  converged  toward  each  other  in 
the  direction  of  the  dip,  and  increasing  if  they 
diverged  from  each  other,  as  can  bo  seen  by  reference 
to  pi.  15,  fig.  12,  which  shows  twro  locations  on  the  lode 
a  b,  the  dip  being  indicated  by  the  arrow.  The 
dotted  lines  show  the  non-parallel  end  lines  prolonged 
in  the  direction  of  the  dip,  and  it  is  plain  that  the 
location  G  would  constantly  be  gaining,  while  D 
would  be  losing  ground  in  depth.  For  this  reason 
the  end  lines  of  a  claim  must  be  kept  parallel  in  justice 
to  both  locators.  It  is  not,  however,  always  an  eas.y 
matter  to  do  this,  the  first  locator  usually  getting  in 
practice  an  advantage  over  his  later  located  neighbor. 

Surface  Length  and  Actual  Lode  Length. — While  the 
grant  says  "1,500  ft.  on  the  vein"it  is  in  reality  1,500 
ft.  on  the  line  of  the  outcrop  of  the  vein  measured 
horizontally,  and  by  varying  the  angle  between  the 


184         PROSPECTING  AND   VALUING  MINES. 

end  lines  and  the  lode  line,  the  locator  may  acquire 
either  less  than  1,500  ft.  measured  horizontally  on  the 
real  vein  or  a  great  deal  more.  Take  for  instance  the 
case  presented  in  pi.  14,  fig.  1,  in  which  AB  shows  a 
location  of  1,500  ft.  on  the  outcrop  of  the  vein  AC,  a 
tunnel  on  the  vein  starting  on  the  outcrop  at  A  and 
terminating  at  C,  on  the  prolongation  of  the  end  line 
of  the  location  DE,  which  is  made  at  right  angles  to 
the  lode  line.  The  dip  of  the  vein  in  the  direction  of 
the  arrow  is  60°  from  the  horizontal,  and  the  rise 
of  the  mountain  side  on  which  the  outcrop  is  located 
from  A  to  B  is  500  ft.  Fig.  2  shows  a  cross  section 
of  the  lode  on  the  line  CDE  in  fig.  1,  and  the  dimen- 
sions just  given  make  the  horizontal  distance  from 
BB,  which  is  vertically  under  the  point  B  on  the  out- 
crop on  the  end  line,  to  the  tunnel  at  C  287  ft.  (ignor- 
ing fractions).  Returning  to  fig.  1,  the  line  AC,  or 
the  actual  distance  owned  by  the  locator  on  the  lode 
horizontal^,  will  therefore  be  longer  than  the  length 
on  the  outcrop;  viz.,  the  square  root  of  1,500  squared 
plus  287  squared,  or  1,527  ft.  approximately. 

If  the  rise  of  the  outcrop  is  33°,  as  is  not  infre- 
quent, the  height  of  B  above  BBom  C  will  be  817  ft. 
and  the  distance  BC  408.5  ft. ;  and  AC  will  be 
1,546.7  ft. 

But  if  the  dip  of  the  vein  be  45°  and  the  slope  of 
the  outcrop  is  33°,  B  will  be  817  ft.  above  C;  BC  will 
be  817  ft.  long,  and  AC  1,708.2  ft.,  or  208.2  ft.  longer 
than  the  grant  on  the  outcrop. 

Hence  it  can  readily  be  seen  that  the  apparently  un- 
important question  of  the  position  of  the  end  lines  in 
really  one  of  great  importance  to  the  owner,  when  the 
lode  has  a  flat  dip  and  crops  on  steep  hillsides,  cut- 
ting a  smaller  and  smaller  figure  as  the  country  be- 
comes flatter  or  the  lode  more  vertical.  "When  per- 
fectly vertical  both  lines  would  be  the  same  length;  as 
also  in  a  level  plain.  (PI.  14,  fig.  1,  is  distorted  to 
give  better  room  for  display.) 


MAKING  LOCATIONS.  185 

When  making  a  single  location  on  a  vein,  rect- 
angular end  lines  may  be  undoubtedly  the  best;  but 
the  reverse  may  be  true  where  a  series  of  such  loca- 
tions are  made,  unless  the  outcrop  of  the  vein  follows 
a  verj'  straight  line,  which  is  only  the  case  when  it  is 
nearly  vertical.  If  sinuous  or  crooked,  as  in  pi.  14, 
fig.  3,  where  a,aa"a"  is  the  outcrop  and  the  arrow 
shows  the  dip,  a  single  location  like  ^will  be  satis- 
factory; but  if  we  add  another,  as  W,  at  a  later  date, 
^will  take  everything  in  depth  between  the  dotted 
lines  ab  and  ab,  while  W  will  only  be  able  to  follow 
the  vein  downward  till  it  encounters  the  line  a'b,  and 
stops  the  shaded  triangle  between  the  lines  a'b  and 
a"c.  If  a  third  location  X  be  made  as  shown,  no  one 
will  own  the  gore  between  the  lines  a'c  and  a"e,  nor 
can  title  be  acquired  thereto,  because  there  is  no 
vacant  ground  on  the  outcrop  at  a"  on  which  to  base  a 
location.  This  is,  of  course,  an  extreme  case,  but  if 
all  the  locations  are  made  in  the  interest  of  the  same 
parties,  it  is  evidently  better  that  the  end  lines  should 
be  made  as  in  pi.  14,  fig.  4,  because  the  distance  on  a 
horizontal  line  between  the  end  lines  ab  and  hh  would 
always  remain  the  same,  at  any  depth;  whereas  in  fig. 
3  the  end  lines  ab  and  a'"h  converge,  and  would  ulti- 
mately intersect  each  other  and  cut  out  the  ownership 
of  the  lode  completely. 

Puzzling  Locations. — It  may  be  well  to  call  atten- 
tion to  some  other  defective  forms  which  result  from  a 
vein  with  a  dip,  traversing  a  hilly  country  cut  up  with 
deep  ravines,  producing  the  results  discussed  in  the 
subject  of  outcrops  and  illustrated  in  pi.  9,  figs.  3  and 
5,  and  from  the  frequent  want  of  a  continuous  out- 
crop. If  the  ore  chutes  are  as  shown  in  pi.  9,  fig.  7, 
the  outcrops  would  be  conspicuous  on  one  side  of  the 
ravines  as  at  cc,  but  would  be  scarcely  visible  on  the 
other,  as  at  dd.  In  a  plan  these  outcrops  would  be  seen 
as  at  aa  in  pi.  14,  tig.  5,  which  shows  two  ravines  with 
intervening  hills.  For  want  of  knowledge  how  to 


186         PROSPECTING  AND  VALUING  MINES. 

trace  a  vein,  a  great  number  of  locations  are  made  by 
continuing  the  line  of  the  visible  outcrop  as  in  the 
locations  ZZ  in  a  straight  line,  but  if  the  dotted  lines 
show  the  connecting  portion  of  the  vein,  not  exposed, 
it  is  evident  that  it  will  pass  out  of  the  side  lines  of 
the  locations  at  bb.  The  complications  which  could 
arise  from  such  a  condition  of  things,  on  working  the 
lodes,  are  almost  endless,  varying  according;  to  the 
priority  of  location  and  the  direction  of  the  dip  of  the 
vein. 

Another  form  of  trouble  arising  from  the  same 
causes  is  shown  in  pi.  14,  fig.  6,  in  which  aa  are  the 
outcrops  of  the  same  vein,  on  two  sides  of  a  ravine, 
the  connection  between  the  two  not  being  visible  on 
account  of  accumulated  debris  in  the  stream  bottom. 
Instead  of  two  locations  crossing  each  other,  a  single 
location  should  have  been  made  following  the  solid 
lines,  but  modifying  the  direction  of  the  end  lines  as 
shown.  Such  a  location,  while  having  1,500  ft.  on 
the  outcrop,  would  have  a  shorter  length  on  the  vein, 
but  whatever  this  might  be,  it  would  remain  uniform. 

In  granite  countries,  especially,  the  ore  bodies  may 
be  short,  lying  in  the  vein  somewhat  as  shown  in  pi. 

6,  fig.   5,    where  the    peculiarity    is    exaggerated    for 
illustration,  and  may  present  themselves  as  a  series  of 
short,  more  or  less  parallel  outcrops,  as  in  pi.  14,  fig. 

7,  aaa.     These  are  often   made  the  basis  of  a  series  of 
locations  as  XXX,  when    the    true  line  of  the  vein   is 
shown  by  the   dotted   line,  and   two  locations,  as  ZZ, 
might  have  covered  the  property  at  a  saving  of  several 
hundred  dollars. 


CHAPTEE  XL 
PATENTS  TO  MINING  GROUND. 

IN  the  States  and  Territories  where  the  United 
States  mining  law  is  operative  the  acquisition  of  title 
in  fee  simple  to  mineral  land  is  somewhat  more  com- 
plicated than  to  agricultural  lands,  as  special  surveys 
must  be  made  in  most  cases  to  separate  it  from  the 
latter,  except  in  the  case  of  coal  and  stone  lands,  which 
are  sold  by  subdivisions  of  the  ordinary  land  surveys; 
or  in  the  case  of  placer  ground  where  the  government 
surveys  have  already  been  extended  over  the  placer 
area,  in  which  latter  case  the  land  can  only  be  taken 
iii  the  usual  legal  subdivisions,  except  that  the  selec- 
tion can  be  made  in  as  small  quantities  as  10-acre 
tracts.  But  in  all  cases  of  application  for  patent  to 
mineral  land  a  full  description  by  exterior  boundaries, 
or  by  legal  subdivisions,  must  be  published,  so  as  to 
allow  an  opportunity  for  agricultural  claimants  or 
others  to  contest  the  application,  if  so  inclined. 

Except  where  special  surveys  have  to  be  made  to 
segregate  the  mineral  land  from  the  surrounding 
agricultural  area,  the  proceedings  originate  in  the 
"United  States  land  office  for  the  district  in  which  the 
land  may  be  situated ;  but  where  surveys  have  to  be 
made  they  originate  in  the  office  of  the  United  States 
surveyor-general  for  the  State  in  which  the  locations 
lies.  Thus  the  United  States  surveyor-general  deals 
only  with  those  claims  which  require  special  surveys; 
and  to  these  w?e  will  first  give  attention,  as  they 
include  the  much  larger  proportion  of  mineral  loca- 
tions. 


188         PROSPECTING  AND  VALUING  MINES. 

Before  going  further  it  will  be  well  to  note  the  dif- 
ference between  a  "location"  and  a  "claim,"  as  the 
words  are  often  used  indiscriminately,  although  in  land 
office  proceedings  they  have  distinct  and  very  differ- 
ent meanings.  A  lode  location  must  not  exceed  1,500 
ft.  in  length  by  600  ft.  in  width;  and  a  placer  loca- 
tion must  not  contain  more  than  20  acres,  but  may  be 
of  any  shape  necessary  to  cover  the  ground  sought  to 
be  purchased.  On  the  other  hand  a  claim  may  include 
as  many  locations  as  the  owner  or  claimant  may  have 
been  able  to  purchase,  provided  they  are  adjacent  to 
each  other,  and  a  patent  for  a  single  claim  may  con- 
tain many  locations.  In  such  a  consolidated  survey 
and  patent  the  aggregate  of  say  eight  placer  locations 
must  not  exceed  160  acres,  and  no  one  of  the  individ- 
ual locations  must  exceed  20  acres;  if  any  of  the  loca- 
tions fall  short  of  20  acres,  the  loss  cannot  be  made 
good  by  allowing  an  excess  in  some  other  location. 

Procedure  on  all  Lode  Locations,  and  such  Placer 
Locations  as  Lie  on  Unsurveyed  Land.' — In  these 
matters  a  uniform  process  must  be  gone  through 
and  a  rigid  adherence  to  the  routine  of  the  surveyor- 
general's  office,  as  well  as  that  of  the  local  land  office, 
will  greatly  facilitate  progress. 

Duties  of  the  Surveyor. — All  mineral  surveys  in- 
tended to  form  the  basis  of  an  application  for  a  United 
States  patent  must  be  made  by  a  deputy  mineral  sur- 
veyor. These  deputies  are  appointed  by  the  United 
States  surveyor-general  for  the  State,  and  are  placed 
under  bonds  for  $10,000,  with  two  sureties,  qualifying 
in  double  the  amount,  for  the  faithful  performance  of 
their  duties,  which  are  carefully  defined  in  the  gov- 
ernment instructions,  and  from  which  there  can  be  no 
diviation  without  the  risk  of  serious  trouble  both  to 
the  surveyor  and  the  applicant. 

Deputy  Surveyor's  Fees. — The  deputy  is  paid  for 
his  services  by  the  applicant,  who  has  the  right  to 
select  whomever  he  may  prefer,  and  the  compensation 


PATENTS  TO  MINING  GROUND.  189 

for  the  work  is  a  matter  of  agreement  between  the 
applicant  and  the  deputy,  as  there  is  no  recognized 
scale  of  fees;  such  an  arrangement  being  impossible 
on  account  of  the  widely  different  conditions  under 
which  the  surveys  are  made  as  to  accessibility  of  the 
locality,  roughness  of  the  ground  and  number  of  sur- 
veys to  be  made  in  any  one  locality.  It  is  evident  that 
the  incidental  traveling  expenses  will  be  just  as  great 
for  the  survey  of  one  location  as  for  ten,  if  they  are 
in  the  same  vicinity. 

The  following  extracts  from  the  instructions  issued 
to  the  deputy  mineral  surveyors  by  the  surveyor- 
general  for  the  State  of  "Washington  will  show 
the  limit  of  their  authority  and  furnish  a  guide  to 
applicants  for  survey  in  preparing  their  case : 

Field  Work  (7). — The  survey  made  and  reported  must,  in  every  case,  be  an 
actual  survey  of  the  ground  in  full  detail,  made  by  you  in  person  after  the 
receipt  of  the  order,  and  without  reference  to  any  knowledge  you  may  have 
previously  acquired  by  reason  of  having  made  the  location,  survey  or  other- 
wise, and  must  show  the  actual  facts  existing  at  the  time.  If  the  season  of 
the  year,  or  any  other  cause,  render  such  personal  examination  impossible, 
you  will  postpone  the  survey,  and  under  no  circumstances  rely  upon  the 
statements  or  surveys  of  other  parties,  or  upon  a  former  examination  by 
yourself. 

The  term  "  survey  "  in  these  instructions  applies  not  only  to  the  usual  field 
work,  but  also  to  the  examinations  required  in  the  preparation  of  your  affi- 
davits of  $500  expenditure,  descriptive  reports  on  placer  claims,  and  all  other 
reports. 

(4)  No  return  by  you  will  be  recognized  as  official  unless  made  in  pursuance 
of  a  special  order  from  this  office. 

Not  to  Act  as  Attorney  (6).— You  are  precluded  from  acting  either  directly 
or  indirectly  as  attorney  in  mineral  claims.  Your  duty  in  any  particular 
case  ceases  when  you  have  executed  the  survey  and  returned  the  field  notes 
and  preliminary  plat  with  your  report  to  the  surveyor-general.  You  will 
not  be  allowed  to  prepare  for  the  mining  claimant  the  papers  in  support  of  his 
application  for  patent,  or  otherwise  perform  the  duties  of  an  attorney  before 
the  land  office  in  connection  with  a  mineral  claim.  You  are  not  permitted  to 
combine  the  duties  of  surveyor  and  notary  public  in  the  same  case  by  ad- 
ministering oaths  to  parties  in  interest.  In  short,  you  must  have  absolutely 
nothing  to  do  with  the  case  except  in  your  official  capacity  as  surveyor. 
You  will  make  no  survey  of  a  mineral  claim  in  which  you  hold  an  interest. 

Survey  and  Location  (8). — The  survey  must  be  made  in  strict  conformity 
with,  or  be  embraced  within,  the  lines  of  the  recorded  location  upon  which 
the  order  is  based.  If  the  surrey  and  location  are  identical,  that  fact  must 
be  clearly  and  distinctly  stated  in  your  field  notes.  If  not  identical,  a  bear- 
ing and  distance  must  be  given  from  each  established  corner  of  the  survey  to 
the  corresponding  corner  of  the  location.  The  lines  of  the  location  as  found 
upon  the  ground,  must  be  laid  down  upon  the  preliminary  plat  in  such  a 
manner  as  to  contrast  and  show  their  relation  to  the  lines  of  the  survey. 

(11)  In  accordance  with  the  principle  that  courses  and  distances  must  give 
way  when  in  conflict  with  fixed  objects  and  monuments,  you  will  not,  under 
any  circumstances,  change  the  corners  of  the  location  for  the  purpose  of 


190         PROSPECTING  AND   VALUING  MINES. 

making  them  conform  to  the  description  in  the  record.  If  the  difference 
from  the  location  be  slight,  it  may  be  explained  in  the  field  notes,  out  if  there 
should  be  a  wide  discrepancy,  you  will  report  the  facts  to  this  office  and 
await  further  instructions. 

From  the  foregoing  it  will  be  seen  how  important  it 
is  that  everything  should  be  in  good  order  on  the 
ground  before  the  surveyor  is  sent  on  to  it.  There  is 
a  widely  prevalent  idea  that  the  surveyor  can  rectify 
any  irregularities  which  he  may  discover,  and  reestab- 
lish corners  which  may  be  missing,  without  any  prob- 
ability of  future  trouble,  but  this  is  not  the  case.  It 
is  true  he  can  take  testimony  to  ascertain  the  former 
position  of  missing  corners,  but  this  involves  delay  and 
extra  expense  for  which,  in  the  very  large  majority  of 
cases,  the  applicants  are  unwilling  to  pay;  and  as  the 
entire  theory  of  the  mining  laws  is  based  on  the  sup- 
position that  a  party  places  no  value  on  a  neglected 
article  the  applicant  should  not  be  surprised  if  the 
authorities  who  have  to  pass  on  the  legality  of  his  loca- 
tion take  that  view,  and  make  no  excuses  for  things 
which  ought  to  have  been,  and  might  have  been,  in 
better  shape. 

The  duty  of  the  surveyor  is  simply  to  report  the 
facts  as  he  finds  them  on  the  ground;  if  a  stake  or 
monument  is  missing  he  must  so  state,  giving  such 
reasons  as  may  apparently  account  for  its  absence,  at 
the  same  time  leaving  the  examining  authorities  to 
judge  whether  such  reasons  are  satisfactory;  if  the 
monument  is  in  existence  he  must  so  report,  and  if 
not  identical  with  the  corner  of  a  survey  he  must  ex- 
plain why  it  is  not;  he  cannot  increase  the  length  of  a 
claim  if  it  has  been  made  less  than  1,500  ft.  originally  ; 
and  he  must  make  the  end  lines  parallel,  though  the 
side  lines  need  not  necessarily  be  so.  In  fact  he  is 
not  allowed  to  be  in  any  sense  a  judge  of  the  equities 
of  the  case;  he  is  simply  employed  to  collect  the  in- 
formation by  which  others  can  adjust  them. 

Duties  of  the  Applicant. — The  following  extract  is 
from  the  official  instructions; 


PATENTS  TO  MINING  GROUND.  191 

(4)  ...    You  are  therefore  advised,  before  filing  your  application,  to  sec 
that  your  location  has  been  made  in  compliance  with  law  and  regulations, 
and  that  it  properly  describes  the  claim  for  which  patent  is  sought. 

Office  Charges. — There  are  certain  charges  for  work 
in  the  office  of  the  surveyor-general  which  are  indepen- 
dent of  the  contract  with  the  surveyor,  and  are 
intended  to  cover  the  cost  of  examining  the  filed  notes 
of  the  survey  and  the  preparation  in  quadruplicate  of 
the  maps  and  field-notes,  one  copy  of  which  is  sent  to 
Washington  to  the  general  land  office,  two  to  the  ap- 
plicant, and  the  other  is  retained  on  file  in  the  office 
of  the  local  surveyor-general.- 

(5)  With  regard  to  the  platting  of  the  claim  and  other  office  work  in  the 
surveyor-general's  office,  that  officer  will  make  an  estimate  of  the  cost 
thereof,  which  amount  the  claimant  will  deposit  with  any  assistant  United 
States  treasurer,  or  designated  depository,  in  favor  of  the  United  States 
treasurer,  to  be  passed  to  the  credit  of  the  fund  created  by  individual  depos- 
tors  for  surveys  of  the  public  lands,  and  file  with  the  surveyor-general  the 
duplicate  certificate  of  such  deposit  in  the  usual  manner. 

(6)  The  following  is  the  estimated  cost  of  platting  and  other  office  work  in 
connection  with  the  survey  of  mineral  claims  :* 

Lode  claim $35  00 

Placer  claim 35  00 

Mill  site  claim 35  00 

Mill  site  included  in  one  survey  with  a  lode  claim 25  00 

Each  lode  claim  inc  uded  in  the  survey  of  a  placer  claim 25  00 

Several  lode  or  placer  claims  in  one  survey,  each  location , 35  00 

Descriptive  report  on  placer  claim  taken  by  legal  subdivisions 10  00 

(7)  Should  the  office  work,  in  any  case,  amount  to  more  than  the  above 
estimate,  an  additional  deposit  will  be  required. 

(8)  In  districts  where  there  is  no  United  States  depository,  you  should  de- 

Eosit  with  the  nearest  assistant  United  States  treasurer,  or  depository,  and 
i  all  cases  immediately  forward  the  original  certificate  (of  deposit)  to  the 
secretary  of  the  treasury  (at  Washington,  D.  C.)  and  the  duplicate  to  the 
surveyor-general,  retaining  the  triplicate  for  your  own  use  and  security. 
Under  no  circumstances  will  the  deposit  be  made  w  th  the  surveyor -general. 
The  deposits  for  office  work  are  not  to  be  made  until  the  applications  for 
survey  are  received,  and  the  parties  notified  by  the  survey  or- general. 

The  order  of  procedure  is  therefore  as  follows: 
1.  Application  Blanks. — As  applications  for  survey 
must  be  made  on  the  blank  forms  adopted  by  the  sur- 
veyor-general's office,  the  applicant,  unless  he  can 
secure  one  from  the  deputy  surveyor,  should  write  to 
the  surveyor-general  for  a  blank  form. 

Particulars. — This  application  contains  the  name  of 
the  deputy  who  has  been  selected  to  make  the  survey, 

*This  is  the  scale  issued  by  the  State  of  Washington,  and  is  only  given  tc 
convey  a  general  idea  of  the  cost. 


192        PROSPECTING  AND  VALUING  MINES. 

and  a  request  for  an  estimate  of  the  office  fees.  It 
should  also  be  filled  out  with  the  name  of  the  claimant 
in  full,  as  it  is  desired  to  appear  in  the  application  to 
the  land  office  for  patent;  the  name  of  the  mining 
claim  in  full,  stating  whether  it  is  a  lode  or  placer 
claim ;  the  name  of  the  mining  district,  and  the  land 
office  district  in  which  the  claim  is  located,  and  if  the 
claim  is  made  up  of  several  locations,  they  should  all 
be  enumerated  in  detail. 

With  this  application,  there  must  be  forwarded  <fa 
copy  of  the  record  of  location  of  the  claim,  properly 
certified  by  the  recorder  having  charge  of  the  records 
of  the  mining  locations  in  the  county  where  the  claim 
is  situated/'  This  may  be  either  the  recorder  of  the 
mining  district,  if  one  has  been  regularly  organized, 
or  the  county  recorder  if  no  district  has  been  formed, 
or  the  organization  has  been  abandoned  or  fallen  into 
disuse.  When  securing  this  certified  copy  of  the 
notice  of  location,  a  second  one  should  be  secured  and 
delivered  to  the  deputy  who  is  to  make  the  survey,  as 
he  has  to  make  the  survey  in  conformity  with  the 
notice  and  return  it  to  the  surveyor-general  as  a  por- 
tion of  his  field-notes.  The  deputy  has  also  to  file 
with  his  returns  a  copy  of  the  laws  of  the  mining  dis- 
trict, if  such  be  organized,  and  it  is  important  that 
the  location  should  conform  to  these  laws  and  regula- 
tions. A  local  miners'  organization  may  impose  any 
conditions  they  see  fit  on  a  locator,  provided  they  do 
not  conflict  with  the  general  mining  laws  of  the  United 
States,  and  as  long  as  such  local  rules  are  in  force  in 
a  district,  any  application  which  takes  an  amount  in 
excess  of  the  local  regulations  is  liable  to  be  returned 
for  correction. 

2.  Deposit;  Receipt;  Order  for  Survey. — When  ap- 
plication for  survey  has  been  filed  with  the  ^surveyor- 
general,  he  will  notify  the  applicant  of  the  cost  of  the 
office  work,  and  this  sum  must  be  deposited  as  previ- 
ously explained.  On  the  receipt  of  the  duplicate 


PATENTS  TO  MINING  GROUND.  193 

receipt,  showing  that  the  charges  have  been  deposited 
to  his  credit,  the  surveyor-general  issues  his  order  of 
survey  to  the  deputy  mineral  surveyor,  who  can  make 
no  official  move  until  he  is  in  receipt  of  this  authoriz- 
ation. The  applicant  has  nothing  further  to  do  until 
the  survey  is  completed,  and  has  been  examined  and 
platted  by  the  proper  authorities. 

As  the  surveyor  has  to  make  with  his  returns  a 
statement  of  the  value  of  the  work  done  on  the  loca- 
tion, supported  by  the  affidavit  of  two  disinterested 
persons,  the  applicants  should  be  careful  that  fully 
$500  has  been  expended  in  actual  mining  improve- 
ments, as  if  this  has  not  been  done,  the  papers  are 
likely  to  be  returned,  involving  loss  of  time  and  ex- 
pense. The  common  notion  that  $5  should  be  allowed 
for  each  day's  work  on  the  location  is  erroneous; 
labor  should  be  counted  at  its  current  rate,  whatever 
it  may  be,  and  to  estimate  a  man's  labor  at  $5  per 
diem  for  the  purpose  of  securing  patent  to  the  ground 
and  only  at  $2  per  diem  for  other  purposes  suggests  a 
fraudulent  intent,  and  may  lead  to  trouble,  as  it  is  not 
carrying  out  either  the  letter  or  the  spirit  of  the  law. 
It  is  evident  that  if  the  location  is  worth  patenting  at 
all,  it  is  worth  honest  returns  as  to  the  value  of  the 
improvement,  by  which  is  meant  the  actual  amount  of 
money  spent  upon  the  ground,  in  which  estimate 
traveling  expenses  and  such  other  items  are  not 
allowed. 

3.  Publication. — When  the  returns  of  the  surveyor 
have  been  examined  and  approved  by  the  surveyor- 
general,  he  forwards  to  the  applicant  two  copies  of  the 
field-notes  and  two  copies  of  the  official  plat.  The 
applicant  must  then  make  an  agreement  with  the 
nearest  local  newspaper  for  the  publication  of  the  notice 
of  intention  to  apply  for  a  patent,  which  notice  must 
contain  such  a  description  of  the  ground,  made  up  from 
the  field-notes  sent  by  the  surveyor-general,  as  will 
fully  identify  the  ground  and  give  notice  to  all  adjacent 


194         PliOSPymXNQ  AND  VALUING  MINES. 

owners  and  others  of  what  ground  is  claimed.  This 
notice  must  be  published  60  days,  or  if  in  a  weekly 
paper  it  must  appear  in  nine  consecutive  issues.  When 
this  publication  is  decided  on,  the  applicant  must  post 
one  copy  of  the  map  and  field-notes  upon  the  claim.. 
in  some  conspicuous  place,  in  the  presence  of  two 
witnesses,  who  must  be  disinterested  parties,  and 
this  notice  must  remain  on  the  ground  during  the 
entire  period  of  publication. 

During  this  period  of  publication,  any  one  has  the 
right  to  file  an  adverse  claim  to  the  ground,  but  if 
such  claim  is  not  filed  during  this  period  the  adverse 
claimant  is  debarred  from  further  proceedings.  Such 
adverse  claim  when  filed  must  be  accompanied  with  a 
plat  of  the  ground  showing  the  conflict  of  interest,  for 
the  information  of  the  prior  claimant,  and  suit  must 
be  commenced  within  30  clays  in  the  proper  court,  to 
determine  the  respective  rights  of  the  parties,  and 
such  suit  must  be  prosecuted  with  diligence  to  a  termi- 
nation. Evident  negligence  to  do  this  justifies  the 
land  office  in  taking  steps  to  force  it,  or  dismiss  the 
adverse  claim. 

Documents  to  be  Filed;  Final  Proof. — If  there  be 
no  adverse  claim  filed,  the  applicant  is  then  ready  to 
proceed  with  his  final  proof  before  the  United  States 
land  office  for  the  district  in  which  the  claim  is  situ- 
ated, and  will  be  required  to  file  the  following  papers 
in  the  case : 

1.  Application  for  patent,  on  the  usual  blank  forms,  which  must  be  in  the 
name  of  the  party  or  parties,  or  incorporation,  making  the  application  for 
survey. 

2.  The  copy  of  the  surveyor-general's  official  plat,  with  the  accompanying 
field  notes. 

8.  A  complete  abstract  of  title,  properly  certified  by  the  proper  authori- 
ties. 

4.  Affidavit  of  citizenship,  or  in  the  case  of  an  incorporated  company,  of 
such  incorporation,  as  no  patent  can  issue  to  an  alien. 

5.  Affidavit  by  two  disinterested  parties  of  the  posting  on  the  ground  of  the 
notice  to  apply  for  a  patent,  giving  date  of  posting  and  locality  at  which  it 
was  posted. 

6.  Affidavit  by  two  disinterested  parties  that  such  documents  remained 
continuously  posted  during  the  entire  period  of  the  publication  of  the  notice 
to  apply  for  patent  in  the  newspaper. 

7.  Agreement  with  the  publisher  as  to  cost. 


PATENTS  TO  MINING  GROUND,  195 

8.  A  copy  of  the  notice  of  publication,  cut  from  the  paper. 

9.  Affidavit  of  the  publisher  that  such  notice  was  published  the  requisite 
number  of  times,  giving  the  dates,  name  of  paper,  and  place  of  publication. 

30.  Certificate  of  the  clerk  of  the  Superior  Court  that  there  is  no  suit  pend- 
ing affecting  the  ownership  of  a  title  to  the  ground. 

11.  Affidavit  of  two  disinterested  parties  as  to  the  value  of  the  work  done 
and  its  character.    (These  must  be  actual  mining  improvements.    Houses, 
roads  and  trails  are  not  considered  necessarily  mining  works,  unless  they  are 
connected  with  tunnels,  shafts,  or  other  mining  excavations). 

12.  Affidavit  by  the  applicant  of  the  costs  which  have   been  incurred  in 
securing  the  patent,  including  such  items  as  monies  paid  the  surveyor,  pub- 
lisher, attorney,  etc.    (The  object  of  this  is  twofold  :    (1)  To  protect  the  ap- 
plicant against  exorbitant  charges;  and  (2)  to  protect  the  government  by 
disclosing  whether  prices  have  been  paid  which  might  be  inferred  to  have 
influenced  the  judgment  of  the  person  receiving  them. 

13.  Application  to  purchase. 

Payment  need  not  be  made  on  the  day  on  which  the 
"final  proof "  is  made  in  the  land  office,  by  the  pres- 
entation and  approval  of  all  the  papers  in  the  case, 
but  good  policy  involves  prompt  attention  to  this,  as 
the  payment  of  the  money  due  the  government  is  ac- 
knowledged by  the  issuance  of  a  "duplicate  receipt" 
which  stands  in  the  place  of  a  patent,  and  answers 
every  purpose  of  such  a  document,  until  the  patent  is 
issued,  which  is  a  matter  of  routine  in  Washington 
and  may  not  be  reached  for  a  year. 

Government  Land  Prices. — The  price  for  lode  loca- 
tions and  mill  sites  is  $5  per  acre;  for  placer  ground 
$2.50  per  acre;  and  for  coal  lands  $20  per  acre. 

Contests.—  The  foregoing  proceedings  in  the  land 
office  are  practically  applicable  to  all  mineral  lands, 
and  apply  to  all  simple  uncontested  cases.  The  United 
States  land  office  is  also  the  referee  where  there  may  be 
a  difference  of  opinion  as  to  the  character  of  the  land, 
as  between  mineral  and  agricultural  claimants,  the 
contestants  presenting  their  individual  views  by  testi- 
mony, but  all  questions  of  ownership  are  decided  by 
the  courts.  These  may  include  priority  of  location, 
overlapping  of  locations,  intersecting  or  cross  veins 
and  so  many  other  contingencies  that  in  all  cases  of 
conflict  the  services  of  an  attorney  must  be  called  in. 
This  chapter  is  intended  only  as  a  guide  in  those  cases 
where  all  is  plain  sailing.  In  all  others  a  good  special 
land  lawyer  should  be  consulted. 


196         PROSPECTING  AND  VALUING  MINES. 

Further  Instructions. — The  following  extracts  from 
the  circulars  issued  for  the  guidance  of  deputy  sur- 
veyors may  be  of  interest: 

13.  The  order  of  approval  of  surveys  of  mineral  claims  is  prescribed  by 
general  land  office  circular,  dated  March  3,  1881,  as  follows: 

"  The  mining  survey  first  applied  for  shall  have  priority  of  action  in  all  its 
stages  in  the  office  of  the  surveyor-general,  including  the  delivery  thereof, 
over  any  other  survey  of  the  same  ground  or  any  portion  thereof.11 

"When  the  survey  first  authorized  is  not  returned  within  a  reasonable 
period,  and  the  applicant  for  a  conflicting  survey  makes  affidavit  that  he  be- 
lieves (stating  the  reasons  for  his  belief),  that  such  first  applicant  has  aban- 
doned his  purpose  of  having  a  survey  made,  or  is  deferring  it  for  vexatious 
purposes,  to  wit,  to  postpone  the  subsequent  applicant,  the  surveyor-general 
shall  give  notice  of  such  charges  to  such  first  applicant,  and  call  upon  him 
for  an  explanation  under  oath  of  the  delay.  He  shall  also  require  the  deputy 
mineral  surveyor  to  make  a  full  statement  in  writing,  explanatory  of  the 
delay;  and  if  the  surveyor-general  shall  conclude  that  good  and  sufficient 
reasons  for  such  delay  do  not  exist,  he  shall  authorize  the  applicant  for  the 
conflicting  survey  to  proceed  with  the  same;  otherwise,  the  order  of  proceed- 
ing shall  not  be  changed.11 

"  Whenever  an  applicant  for  a  survey  shall  have  reason  to  suppose  that  a 
conflicting  claimant  will  also  apply  for  a  survey  for  patent,  he  may  give  a 
notice  in  writing  to  the  surveyor-general,  particularly  describing  such  claim, 
and  file  a  copy  of  the  notice  of  location  of  such  conflicting  claim.  In  such 
case  the  surveyor-general  will  not  order  or  authorize  any  survey  of  such 
conflicting  claim  until  the  survey  first  applied  for  has  been  examined,  com- 
pleted, approved  and  platted,  and  the  plats  delivered.11 

13.  Your  attention  is  directed  to  the  first  .  .  paragraphs  of  general  land 
office  circular  dated  December  4,  1884,  viz  : 

"1.  The  rights  granted  to  locators  under  section  2322,  Revised  Statutes, 
are  restricted  to  such  locations  on  veins,  lodes  or  ledgos  as  may  be  *  situated 
on  the  public  domain.'1  In  applications  for  lode  claims  where  the  survey 
conflicts  with  a  prior  valid  lode  claim  or  entry,  and  the  ground  in  conflict  is 
excluded,  the  applicant  not  only  has  no  right  to  the  excluded  ground,  but  he 
has  no  right  to  that  portion  of  any  vein  or  lode  the  top  or  apex  of  which  lies 
within  such  excluded  ground,  unless  his  location  was  prior  to  May  10,  1872. 
His  right  to  the  lode  claimed  terminates  where  the  lode,  in  its  onward  course 
or  strike  intersects  the  exterior  boundary  of  such  excluded  ground  and 
passes  within  it.11 

"2.  The  end-line  of  his  survey  should  not,  therefore,  be  established  beyond 
such  intersection,  unless  it  should  be  necessary  so  to  do  for  the  purpose  of 
including  ground  held  and  claimed  under  a  location  which  was  made  upon 
public  land  and  valid  at  the  time  it  was  made.  To  include  such  ground 
(which  may  possibly  include  other  lodes)  the  end-line  of  the  survey  may  be 
established  within  the  conflicting  survey,  but  the  line  must  be  so  run  as  not 
to  extend  any  further  into  the  conflicting  survey  than  may  be  necessary  to 
make  such  end-line  parallel  to  the  other  end-line." 


CHAPTER  XIL 

EARLY  DEVELOPMENT  OF  MINES. 

WHEN  satisfied  from  thorough  examination  of  the 
surface  indications  that  a  deposit  of  mineral  is  worthy 
of  further  exploration,  the  question  arises  as  to  what 
the  character  of  these  explorations  shall  be,  to  accom- 
plish the  best  results  in  the  shortest  time  and  at  the 
least  expense. 

"Follow  the  Ore." — There  is  one  rule  from  which 
there  should  be  no  variation,  whatever  plan  may  be 
adopted,  in  all  preliminary  works,  and  that  is,  to  fol- 
low the  ore  wherever  it  may  go,  no  matter  how  crooked 
the  shape  of  the  developments  may  be;  as  it  is  only 
by  determining  the  shape  and  character  of  the  deposit 
that  later  works  can  be  laid  out  intelligently  and  eco- 
nomically. This  plan  has  also  the  advantage  of  to 
some  extent  paying  for  the  work  of  development;  as, 
if  the  ore  is  rich  enough  to  ship,  it  will  furnish  a  cer- 
tain amount  of  cash  to  continue  the  work,  while  at  the 
same  time  such  shipments  will  attract  the  attention  of 
mining  men,  and  go  far  toward  effecting  a  sale  if  this 
is  contemplated,  or  securing  aid  to  prosecute  the  work 
on  a  larger  scale.  Even  if  the  ore  be  too  poor  to  ship, 
the  dump  may  yet  be  a  valuable  asset,  and  the  number 
of  tons  it  contains  will  be  evidence  of  the  faith  of  the 
owners  in  their  property,  and  will  furnish  a  better  evi- 
de'nce  of  the  producing  capacity  of  the  property  than 
any  series  of  mere  measurements. 

Cross-cut  Tunnels. — How  often  this  rule  is  disre- 
garded may  be  seen  by  the  frequent  newspaper  notices 


198        PROSPECTING  AND  VALUING  MINES, 

that  ''so-and-so  have  started  a  tunnel  to  tap  the  vein 
200  ft.  deep/'  or  some  other  attractive  figure,  when  in 
all  probability  the  deepest  hole  on  the  property  may 
not  be  10  ft.  deep.  Such  schemes  are  usually  based 
on  the  mistaken  idea  so  often  heard  repeated,  that  the 
mine  will  "show  up"  in  depth.  Deep  cross-cut  tun- 
nels are  admissible  for  working  purposes  when  the 
mine  is  proved  to  be  worth  the  cost  of  driving  them, 
but  thev  are  unadvisable  at  the  beginning  of  opera- 
tions, unless  it  is  impossible  to  approach  the  ore  body 
in  any  other  way;  and  in  such  cases  the  surface  show- 
ing must  be  more  than  ordinarily  good  to  justify  such 
a  procedure.  Such  early  works  have  two  fatal  defects  : 
(1)  A  shaft  must  be  sunk  ultimately,  connecting  the 
surface  and  tunnel  to  give  ventilation,  and  good  policy 
would  indicate  the  propriety  of  sinking  the  shaft  first, 
and  running  the  tunnel  afterward  to  meet  it,  if  the 
showing  in  the  shaft  justified  it;  and  (2)  such  a  cross- 
cut tunnel  through  the  rocks  which  inclose  the  vein 
may  cut  the  vein  where  it  is  barren  or  in  a  " pinch," 
and  cause  the  abandonment  of  the  property ;  and  at  the 
best,  after  months  of  work,  it  tells  us  the  character  of 
the  ore  and  the  thickness  of  the  vein  or  deposit  at  the 
single  point  where  it  is  encountered,  when  we  ought 
to  be  learning  something  daily  for  every  dollar  ex- 
pended. The  point  where  the  vein  is  cut  may  be 
much  poorer  than  the  ore  on  either  side  at  compar- 
atively short  distances  away,  causing  an  underestimate 
of  the  value  of  the  property;  or  the  ore  encountered 
may  be  a  rich  bunch,  giving  exaggerated  ideas  of  value ; 
or  the  ore  may  have  thinned  out  and  disappeared  alto- 
gether, which  fact  would  have  been  demonstrated 
much  earlier  in  a  shaft.  Such  a  tunnel,  unless  fol- 
lowed up  by  explorations  of  the  vein  laterally,  adds 
little  to  the  value  of  a  property  which  may  be  offered 
for  sale,  because  it  does  not  prove  continuous  ore  from 
the  surface  to  the  depth  at  which  it  cuts  the  lode — it 
only  renders  it  probable;  while  the  same  money  spent 


EARL  Y  DEVELOPMENT  OF  MINES.  199 

in  sinking  on  the  vein  might  have  produced  a  market- 
able proposition,  or  proved  the  smallness  of  the  ore 
body  at  much  less  cost.  A  tunnel  to  tap  ihe  vein,  200 
ft.  deep,  is  not  likely  to  be  less  than  300  ft.  long,  and 
when  completed  and  without  drifts,  only  exposes  an 
area  of  the  vein  some  5  by  7  ft.  in  extent,  while  a 
shaft  80  ft.  deep,  and  220  ft.  of  drifts  and  cross-cuts 
(300  ft.  of  work  in  all)  would  demand  the  attention  of 
anybody  looking  through  a  mining  camp  with  a  view 
to  purchase.  Sinking  even  small  shafts  or  inclines  is 
of  course  rather  more  expensive  than  tunneling,  es- 
pecially if  the  mine  is  at  all  wet;  on  the  other  hand, 
it  is  quite  possible  that  the  ore  followed  down  and 
taken  out  as  sinking  progresses  may  make  up  the  dif- 
ference. 

Depth  of  Tunnel  Connections. — Many  erroneous  esti- 
mates are  made  of  the  depth  at  which  a  tunnel  of  a 
given  length  will  tap  a  vein,  unless  actual  survey 
has  been  made  instrumentally,  the  tendency  being 
almost  always  to  overestimate  the  depth.  The  best 
guide  is  to  note  the  condition  of  the  surface.  Long 
rock  slides  and  mining  dumps  usually  stand  at  angles 
varying  from  30°  to  35°,  which  figures  give  respec- 
tively a  rise  or  fall  of  from  58  to  67  ft.,  or  an  average 
of  about  63  ft.  in  100.  To  get  200  ft.  of  depth  in  a 
distance  of  200  ft.,  the  angle  will  be  45°,  a  very  steep 
climb,  and  this  occurs  only  in  very  precipitous 
regions. 

Tunnels  in  Foot  or  Hanging  Wall. —Disappoint- 
ment also  results  from  running  the  tunnel  in  the  foot 
wall  of  the  vein,  because  in  addition  to  the  distance 
necessary  to  reach  a  vertical  shaft  sunk  on  the  out- 
crop, if  such  existed,  there  must  be  added  the  addi- 
tional distance  caused  by  the  lode  dipping  away  from 
the  mouth  of  the  tunnel,  which  is  often  forgotten. 
Such  tunnels,  if  they  must  be  run  in  early  develop- 
ment, should  be  run  if  possible  in  the  hanging  wall, 
so  as  to  take  advantage  of  the  vein  approaching  the 
tunnel  on  its  dip  in  depth. 


200        PROSPECTING  AND  VALUING  MINES. 

Drift  Tunnels. — Two  other  methods  of  early  develop- 
ment are  possible — one  by  sinking  on  the  vein,  the 
other  by  tunneling,  or  rather  drifting  on  it,  starting 
on  the  outcrop  and  following  in  on  the  lode.  This 
last  method  is  by  far  the  most  satisfactory,  as  ifc  proves 
both  length  and  depth,  for  if  the  ore  is  continuous  in 
the  tunnel  and  in  the  outcrop  overhead,  we  are  justi- 
fied in  considering  that  it  is  continuous  to  the  depth 
of  the  tunnel,  and  below,  if  it  shows  in  the  floor  of  the 
drift,  and  the  mine  has  then  what  is  known  as  "re- 
serves," or  ore  proved  and  merely  waiting  extraction. 
This  method  of  development  also  possesses  the  advan- 
tage (which  may  often  be  an  inducement  to  run  the 
cross-cut  tunnels  just  discussed)  of  one  man  being 
able  to  work  alone,  using  alternately  the  pick  or 
single-hand  drill  and  wheelbarrow;  and  upraises 
can  be  made  from  time  to  time  to  the  surface  with 
ease,  as  the  material  mined  falls  of  its  own  weight  to 
the  floor  of  the  drift,  and  can  be  removed  without  ad- 
ditional labor.  If  timbering  is  to  be  done  two  men 
are  almost  essential,  and  it  may  not  be  advisable 
under  any  circumstances  to  work  alone  in  a  tunnel  in 
loose  ground,  on  account  of  the  risk  of  accidents,  but 
it  can  be  done  in  an  emergency. 

Sinking  on  the  Deposit. — There  are,  however,  many 
cases  where  we  cannot  at  once  drift  on  the  lode,  as  the 
desirable  localities  maybe  covered  by  heavy  debris, 
and  the  exact  location  of  the  vein  unascertainable,  and 
we  must  then  resort  to  sinking  on  the  deposit.  Here 
again  we  must  follow  the  ore,  whether  it  makes  the 
shaft  vertical  or  converts  it  into  an  incline.  At  first 
one  man  at  the  windlass  will  do,  and  two  men  can 
manage  for  a  depth  of  80  to  100  ft.  When  this  depth 
is  attained  it  may  be  profitable  to  drift  on  the  lode 
toward  daylight,  through  the  accumulated  surface 
debris,  and  having  reached  daylight,  to  continue 
operations  by  drifting  on  the  vein ;  or  if  it  is  desired 
to  sink  deeper,  a  horse  whim  will  be  able  to  hoist 
from  a  depth  of  200  ft.^  or  somewhat  more. 


EARL  Y  DE  VELOPMENT  OF  MINKS.  201 

In  sinking  by  hand  regard  should  be  had  to  the  size 
of  the  barrel  or  spindle  of  the  windlass  on  which  the 
rope  is  wound,  as  it  requires  less  power  to  raise  a 
heavy  bucket  slowly  than  rapidly.  The  size  of  the 
spindle  should  therefore  be  smaller  (say  Gin.)  for  deep 
work  than  for  shallow  pits,  not  only  because  a  small 
spindle  raises  the  bucket  a  shorter  distance  at  each 
revolution  of  the  crank  and  so  relieves  the  strain,  but 
because  its  diameter  is  rapidly  increased  by  the  wind- 
ing of  the  rope  upon  it,  making  the  strain  greater  and 
greater  as  the  load  approaches  the  top. 

Water. — The  appearance  of  water  in  a  shaft  may, 
however,  modify  all  the  conditions,  and  compel  a 
resort  to  cross-cut  tunnels,  but-  if  present  in  large 
quantities,  and  artificial  drainage  is  possible,  its  pres- 
ence may  be  considered  a  favorable  indication,  as  it  is 
evidence  that  the  fissure  on  which  work  is  being  pros- 
ecuted is  extensive  and  drains  a  large  area,  and  may 
consequently  contain  larger  bodies.  Such  a  condition 
is  certainly  more  promising  than  a  dry  hole  in  which 
the  ore  shows  little  sign  of  decomposition,  or  of  the 
former  circulation  of  water. 

Position  of  Main  Working  Shafts. — Usually,  from 
the  nature  of  the  explorations  and  the  surrounding 
physical  conditions,  especially  where  the  mine  must 
be  worked  on  a  large  scale  by  deep  shafts,  the  loca- 
tion of  such. shafts  in  suitable  relationship  to  the  lode 
is  a  matter  of  much  importance.  When  the  dip  of  the 
vein  or  deposit  is  comparatively  flat  we  may  be  com- 
pelled to  adopt  an  inclined  in  preference  to  a  vertical 
shaft,  unless  it  be  so  flat  that  it  can  be  worked  like  a 
coal  mine,  on  an  almost  horizontal  floor.  But  when 
the  vein  stands  nearly  vertical  the  greater  facilities  for 
operating  a  vertical  shaft  may  make  such  a  plan  desir- 
able. We  must  then  remember  that  all  mining  ex- 
penses increase  with  depth,  and  if  dead  work  has  to 
be  done  to  reach  the  ore  in  the  lode  it  is  better  to  do 
ji'uch  work  near  the  surface,  while  expenses  are,  IQYY  or 


202         PROSPECTING  AND  VALUING  M1NEK. 

moderate,  than  at  greater  depths  where  they  are  high 
and  constantly  increasing.  PL  9,  fig.  2,  illustrates 
this,  showing  a  vein  and  two  shafts  A  and  B,  in  cross 
section  across  the  lode.  B  is  evidently  better  located 
for  economical  working  than  A,  because  in  the  latter 
the  length  of  the  crosscuts  from  the  shaft  steadily  in- 
creases with  depth,  while  in  B  the  longest  crosscuts 
are  near  the  surface,  and,  for  the  depth  shown,  the 
total  amount  of  dead  work  is  much  smaller  than  in  A9 
with  increasing  advantage  for  greater  depth. 

The  same  principle  is  illustrated  in  pi.  9,  fig.  4,  as 
regards  the  position  of  the  shaft  lengthwise  of  the 
vein,  C  being  the  ore  shoot,  with  a  decided  rake  to 
the  left.  (The  rake  usually  diminishes  with  the  in- 
crease of  dip,  being  least  in  vertical  lodes;  and  is  usu- 
ally similar  in  all  the  veins  of  a  district  having  the  same 
general  stri'ke  and  dip.)  Here  B  located  near  the 
center  of  the  outcrop,  would  not  be  in  as  good  a  posi- 
tion as  A,  for  the  reasons  just  given. 

Cross-  Cutting : — In  all  explorations  on  the  vein  un- 
derground, the  importance  of  intelligent  cross-cutting 
is  obvious.  No  ore  bodies  are  fitted  into  a  clean-cut 
fissure  with  mathematical  accuracy.  The  crushing  of 
the  rocks  which  make  the  formation  of  a  mineral  vein 
possible  also  had  a  tendency  to  scatter  the  ore  bodies 
when  formed,  and  because  one  body  of  ore  gives  out 
in  a  drift  it  by  no  means  follows  that  all-  the  ore  has 
given  out  in  the  mine.  It  may  simply  be  shifted 
laterally  to  another  plane  of  the  "sheeting. "  The 
Keystone  mine,  Amador  County,  Cal.,  is  cross-cut  to 
a  width  of  several  hundred  feet  with  profit;  and  it  does 
not  even  do  to  assume  a  perfectly  smooth,  continuous 
rock  face  to  be  either  the  foot  or  hanging  wall,  as  a 
case  in  Colorado  shows,  where  such  a  wall  was  followed 
by  a  drift  for  several  hundred  feet,  and  when  broken 
into  under  a  change  of  management,  proved  to  be  only 
one  side  of  a  more  valuable  body  of  ore  than  had  been 
extracted  by  the  drift. 


EARLY  DEVELOPMENT  OF  MINKS.  203 

Usually  the  distance  to  which  the  cross-cut  may  be 
carried  is  indicated  by  the  condition  of  the  rock 
through  which  it  is  driven.  As  long  as  this  shows 
evident  signs  of  decay  or  change,  or  traces  of  mineral, 
so  long  it  may  be  desirable  to  continue  the  cross-cut; 
but  it  should  be  stopped  as  soon  as  the  rock  assumes 
the  character  of  the  main  body  of  the  wall  rock  visible 
on  the  surface,  and  not  in  contact  with  the  vein.  If 
working  in  limestone  where  the  ore  occurs  in  pockets 
and  chambers  the  little  stringers  of  ore  should  receive 
especial  attention. 

System  in  Development. — In  all  these  operations  the 
watch  word  should  be  utility  and  economy.  Unintel- 
ligent management  may  easily  swamp  an  enterprise 
which  in  proper  hands  would  have  proved  a  success. 
Every  bit  of  w<ork  done  on  a  location  should  be  the 
result  of  a  carefully  planned  scheme,  the  portions  of 
which  will  fit  together  when  completed.  Especially 
should  this  be  the  case  with  the  annual  assessment 
work.  Too  often  the  owner  looks  upon  this  work  as  a 
burden,  and  desires  to  do  just  as  small  an  amount  of 
it  as  will  legally  hold  the  claim  until  he  can  sell  it. 
Such  skimped  work  will  seldom  sell  a  claim.  Few 
realize  that  only  by  putting  work  on  a  mining  loca- 
tion can  it>  in  most  instances,  be  made  a  salable  or 
valuable  proposition;  and  in  a  large  proportion  of 
cases,  for  want  of  judgment,  the  work  done  leaves  the 
property  looking  worse  than  if  nothing  had  been  done 
upon  it. 

Prospect  Pits.- — If  only  small  sums  of  money  are  to 
be  spent  annually,  these  will  be  best  expended  in 
tracing  the  ore  body  by  a  series  of  shallow  pits, 
rather  than  by  starting  short  tunnels  one  after  the 
other  in  places  where  work  is  easy,  only  to  leave 
them  in  barren  ground.  As  at  present  expended, 
most  of  the  money  spent  on  assessment  work  is  prac- 
tically thrown  away,  for  want  of  system. 

Large  surface  excavations,  except  such  as  are  neces- 


204         PROSPECTING  AND  VALUING  MINES. 

sary  to  trace  the  ore,  are  not  desirable,  in  wet  or 
snowy  countries  especially,  as  they  only  serve  to  divert 
the  rain  and  snow  into  the  mine,  from  which  it  may 
later  on  have  to  be  pumped  at  heavy  cost. 

Common  Terms  Used  in  Mining.* — Definitions  of  a  few 
of  these  may  be  in  place  here:  A  "shaft"  is  a  vertical 
opening,  either  on  or  alongside  of  the  vein  if  that  is 
vertical,  or  outside  of  it  (preferably  in  the  hanging 
country)  if  the  lode  has  a  dip,  but  intersecting  it  in 
depth.  An  "incline"  is  a  sloping  shaft,  usually  made 
to  follow  the  vein  or  ore  bed.  It  may  not  be  so  con- 
venient as  a  vertical  shaft  for  working,  but  involves 
less  dead  work  in  opening  a  mine.  A  "winze"  in  a 
shaft  connecting  the  interior  workings,  but  not  com- 
ing to  daylight.  It  may  be  either  vertical  or  an 
inclined  winze.  A  "chute"  (shoot)  is  a  winze  suitably 
lined  to  pass  ore  and  waste  from  the  workings  to  the 
cars  on  a  lower  level.  ("Chute"  is  also  applied  to 
a  pitching  ore  body.)  The  drain  tunnel,  or  lowest 
horizontal  opening  by  which  water  can  be  discharged 
from  the  mine,  is  the  "adit."  "Drifts"  or  "levels" 
run  from  the  shaft  from  time  to  time  as  it  is  deepened; 
and  are  distinguished  from  "tunnels,"  which  have  one 
end  open  at  the  surface — the  distinction  between  a 
tunnel  and  a  drift  being  the  same  as  between  a  shaft 
and  a  winze.  The  face  of  the  drift  is  called  the 
"head"  or  "heading  ;"  ground  from  which  ore  is  being 
taken  between  the  different  levels  is  called  a  "stope," 
and  the  ore  may  be  removed  either  by  digging  down- 
ward, when  the  process  is  called  "underhand  sto- 
ping,"  or  by  working  upward,  in  which  case  the 
operation  is  said  to  be  "overhand"  or  "overhead." 
It  is  evident  that  by  the  latter  method  the  material 
when  broken  down  drops  away  from  the  workman  more 
readily  than  by  the  former,  and  is  usually  the  one  em- 
ployed, unless  circumstances  absolutely  prevent  its 
economical  adoption.  The  timbers  which  are  put  in 
to  keep  the  walls  apart  after  the  extraction  of  the  ore, 


EA  RL  Y  DE  VEL  OP  MEN  T  OF  MINES.  205 

and  also  to  form  working  floors  for  the  miners,  are 
called  "stulls,"  and  the  filling  done  with  the  waste 
material  (in  Cornwall  Battle"),  which  is  never  taken 
from  the  mine,  if  possible  to  utilize  it,  is  called  the 
"gob. "  When  taken  to  the  surface  it  forms  the 
" waste  dump."  An  excessively  large  dump  of  waste 
material  indicates  an  excess  of  dead  work  in  the  mine; 
a  small  one  on  the  other  hand  is  by  no  means  a  bad 
gage  of  prosperity.  The  bottom  of  shafts,  inclines 
and  winzes  into  which  the  water  of  the  mine  drains, 
and  in  which  the  pumps  are  located,  is  known  as  the 
"smnp, "  and  is  necessarily  below  the  lowest  working 
level,  its  depth  being  gaged  according  to  the  amount 
o^  water  to  be  removed  daily. 


CHAPTER  XIII. 

ORES. 

DEFINITIONS. — An  "ore,"  strictly  speaking,  isasingle 
mineral  which  is  a  chemical  compound  of  a  useful 
metal  and  some  other  element  or  acid.  In  common 
usage,  however,  complex  mixtures  of  pure  minerals  are 
considered  arj  single  ores;  while  free  gold,  native 
silver  and  native  copper,  together  with  their  accom- 
panying gangue  minerals,  are  also  classed  as  ore. 
Among  miners  whatever  will  pay  to  treat  or  ship  and 
sell  is  considered  ore,  as  also  low-grade  mineral  which 
might  be  utilized  by  concentration  or  improved  facili- 
ties; but  there  is  an  indefinite  shading  off  into  mate- 
rial containing  traces  of  ore  minerals  but  hopelessly 
unavailable,  and  this  is  not  considered  ore;  neither  are 
gold  gravel  or  platinum  sands  called  ore.  To  avoid 
misunderstanding,  it  is  best  to  distinguish  between  the 
"ore"  (meaning  thereby  the  whole  bulk  of  the  available 
product)  and  the  "ore  mineral"  (usually  very  much 
smaller  in  quantity  in  all  ores  except  those  of  iron, 
manganese,  and  some  lead  and  zinc  ores).  In  this 
connection  will  be  mentioned  only  those  minerals 
which  produce  the  bulk  of  the  useful  metals.  Min- 
eralogists describe  some  850  different  mineral  species, 
of  which  a  considerable  proportion  might  possibly  be 
called  ores;  but  only  a  comparatively  few  are  of  prac- 
tical importance — the  remainder  are  of  interest  only 
to  the  collector  and  scientist.  It  is  believed  thao 
those  here  described  will  be  sufficient  to  enable  the 


ORES.  207 

prospector  to  recognize  nearly  all  which  are  commer- 
cially valuable. 

The  descriptions  are  based  on  those  in  Dana's  "Min- 
eralogy," and  are  supposed  to  apply  to  the  minerals 
in  their  pure,  crystallized  forms,  but  such  items  as 
hardness,  weight,  color  and  streak  are  common  also 
to  the  massive  forms.  To  make  the  descriptions  short 
and  compact  a  few  terms  and  contractions  are  em- 
ployed, which  need  explanation  : 

Adamantine,  resembling  a  diamond. 

Amorphous,  not  crystallized;  without  any  special 
form. 

Arborescent,  resembling  the  growth  of  the  branches 
of  a  tree. 

Botryoidal,  made  up  of  masses  of  varying  size  with 
smooth  rounded  surfaces,  like  grapes. 

Brilliant,  applied  to  surfaces  which  are  perfect 
reflectors  of  lighto 

Brittle,  breaking  easily. 

Compact,  very  close-grained,  not  showing  special 
crystals. 

Conchoidal,  as  applied  to  surfaces  of  fracture, 
means  resembling  the  inside  of  a  clam'  shell  in  shape. 

Concretionary,  made  up  of  particles  which  have 
apparently  grown  together  into  a  solid  mass. 

Ductile,  capable  of  being  drawn  out  into  wire,  or 
elongated. 

Flat,  as  applied  to  fracture,  means  smooth,  like  a 
board. 

Fibrous,  like  a  bundle  of  threads  laid  side  by  side. 

Filiform,  thread-like,  not  massed  together  as  when 
fibrous. 

Foliated,  made  up  of  thin  leaves  like  a  book. 

Granular,  made  up  of  distinct  grains  like  coarse 
sandstone. 

Iridescent,  exhibiting  a  play  of  changeable  rainbow 
colors. 

Malleable,  flattening  under  the  hammer  without 
breaking. 


208         PROSPECTING  AND   VALUING  MINES. 

Mammillary,  made  up  of  many  small  rounded  sur- 
faces like  miniature  breasts;  usually  applied  to  some 
forms  of  incrustations  on  rocks. 

Massive,  not  crystallized. 

Metallic,  when  descriptive  of  luster,  means  resem- 
bling polished  steel,  silver  or  other  metals,  as  opposed 
to  "earthy." 

Micaceous,  made  up  of  thin  plates,  resembling  flakes 
of  mica. 

Oolitic  (o-o-litic),  made  up  of  rounded  particles,  like 
fish  eggs. 

Opaque,  will  not  permit  the  passage  of  light. 

Pisolitic,  made  up  of  rounded  particles  like  peas. 

Eeniform,  kidney-shaped. 

Resinous,  resembling  resin. 

Sectile,  can  be  cut  with  a  knife,  like   lead  or  easier. 

Shining,  opposed  to  "earthy,"  when  describing  the 
"streak." 

Stalactitic,  resembling  the  cylindrical  masses  found 
hanging  from  the  roof  of  limestone  caves,  formed  by 
dripping  water. 

Subconchoidal,  resembling  conch oidal,  but  flatter, 
more  like  the  inside  of  an  oyster  shell  in  form. 

Submetallic,  with  only  a  slight  metallic  luster,  as  a 
tarnished  silver  surface. 

Translucent,  not  perfectly  clear,  but  resembling  an 
egg  when  held  up  before  a  strong  light. 

Transparent,  permitting  the  perfect  passage  of 
light,  like  glass. 

Uneven,  breaking  into  a  rough  face,  like  a  broken 
brick. 

Vitreous,  glassy. 

Waxy,  as  applied  to  luster,  not  quite  so  bright  as 
resinous,  resembling  the  surface  of  clean  beeswax. 

It  would  not  be  possible  to  give  a  good  idea  of  the 
forms  assumed  by  the  crystallized  minerals  without 
numerous  diagrams,  so  that  only  occasional  references 
are  made  to  crystallization,  The  physical  properties 


ORES.  209 

used  are  the  luster,  color,  streak,  hardness,  weight, 
and  manner  of  breaking.  By  the  "streak/'  is  meant 
the  color  of  the  scratch  made  by  a  penknife  or  the 
color  of  the  powdered  mineral.  The  weight  is  the 
specific  gravity  (in  ratio  to  weight  of  equal  bulk  of 
water),  indicated  by  the  letter  G,  and  is  an  important 
item  in  all  concentrating  operations  or  the  sorting  of 
ores.  The  hardness,  indicated  by  the  letter  H,  refers 
to  a  scale  of  hardness,  in  common  use,  in  which  crys- 
tallized varieties  of  the  minerals  mentioned  are  meant: 
1,  talc;  2,  gypsum;  3,  calcite  or  limespar;  4,  fluor- 
spar; 5,  apatite;  6,  feldspar;  7,  quartz;  8,  topaz;  9, 
corundum;  10,  diamond;  so  that  if  a  mineral  is  said 
to  have  a  hardness  of  4  it  would  scratch  3,  but  would 
not  scratch  5. 

GOLD—  Native.—  H.  2.5—3.  G.  15.6—19.5.  Yel- 
low, malleable,  sectile.  The  depth  of  the  yellow  color 
varies  with  the  amount  of  silver  present  in  the  metal, 
being  deepest  in  the  purest  gold.  When  the  value  in 
silver  becomes  equal  to  the  value  of  the  gold,  the 
native  alloy  is  white.  Distinguished  from  all  minerals 
which  it  resembles,  by  flattening  under  the  hammer, 
instead  of  breaking.  The  minerals  for  which  it  is 
most  frequently  mistaken  are  iron  and  copper  pyrites, 
but  it  may  be  distinguished  from  these,  when  in  such 
a  position  that  it  cannot  be  tested  by  the  knife  or 
hammer,  by  turning  the  specimen  completely  round  in 
the  sunlight,  when  it  will  be  found  to  maintain  the 
same  color  and  appearance  in  every  position.  This  is 
not  the  case  with  the  other  minerals  mentioned,  which 
will  also  float  on  the  top  of  quicksilver,  while  gold 
will  sink.  Insoluble  in  simple  acids.  Distinguished 
from  yellow  mica  by  not  splitting. 

Tellurides  of  Gold. — These  minerals  are  not  found 
in  large  quantities,  but  are  associated  with  other  ores, 
and  from  their  want  of  resemblance  to  gold  often 
puzzle  the  prospector,  who  will  get  very  large  assays 
from  samples  which  show  no  free  gold.  The  four 


210          PROSPECTING  AND    VALUING  MINES. 

forms  may  be  distinguished  by  the  following  char- 
acters.  Three  of  them  greatly  resemble  lead,  and  none 
of  them  are  common  enough  to  have  local  names.  The 
important  tellurides  carrying  gold  are: 

Sylvanite.—H.  1.5—2.  G.  7.9—8.3.  Luster  me- 
tallic. Streak  and  color  steel-gray  to  silver-white, 
sometimes  brass-yellow.  Fracture  uneven.  Approxi- 
mate composition:  gold  30,  silver  10,  tellurium  60%. 

Nagyagite.—H.  1—1.5.  G.  6.8—7.2,  Luster  me- 
tallic, brilliant.  Streak  and  color  blackish  lead-gray. 
Opaque.  Sectile.  Composition:  6  to  12%  of  gold 
with  lead  and  tellurium. 

Petzite.—R.  2.5.  G.  8.8—9.4.  Color  between 
steel-gray  and  iron-black,  sometimes  tarnished  with 
peacock  tints.  Streak  iron-black.  Brittle.  Approxi- 
mate composition :  gold  25,  silver  41,  tellurium  34%. 

Calaverite. — Massive,  without  crystalline  structure; 
color  bronze-yellow;  streak  yellowish  gray;  brittle. 
Fracture  uneven.  Approximate  composition:  gold 
41,  silver  3,  and  tellurium  56%. 

SILVER  —Native.— H.  2.5—3.  G.  10.5.  Luster 
metallic.  Color  and  streak  silver-white.  Ductile. 
Tarnishes  easily  to  grayish  black.  Malleable.  Occurs 
as  wire  silver,  crystallized  (arborescent)  or  massive, 
up  to  800  Ib.  in  weight. 

Argenlite,  Silver  Sulphide,  Vitreous  Silver,  or  Silver 
Glance.— H.  2—2.5.  G.  7.2—7.4.  Luster  metallic. 
Streak  and  color  blackish  lead-gray;  streak  shining. 
Opaque.  Perfectly  sectile.  Occuis  crystallized, 
amorphous,  arborescent  and  filiform.  Approximate 
composition;  silver  85,  sulphur  15%.  Gives  silver 
when  heated  on  charcoal  before  the  blowpipe. 

Pyrargyrite,  Dark  Ruby  or  Antimonial  Ruby  Silver. 
— H.  2—2.5.  G.  5.8.  Luster  metallic.  Color 
black,  sometimes  approaching  dark  or  purplish  red. 
Streak  cochineal-red.  Translucent  to  opaque.  Frac- 
ture conchoidal.  Powder  purplish  red.  Approxi- 
mate composition :  silver  60,  antimony  22,  sulphur 
18%.  Decomposed  by  nitric  acid. 


ORES.  211 

Proustite,  Light  Red  or  Arsenical  Ruby  Silver.* — H. 
2 — 2.5.  G.  5.5.  Luster  adamantine.  Color  cochi- 
neal-red. Streak  cochineal-red  sometimes  brighter. 
Subtranslucent.  Fracture  conchoidal,  uneven.  Pow- 
der bright  red.  Approximate  composition  ;  silver  65, 
arsenic  15,  sulphur  20%.  Decomposed  by  nitric  acid. 

Freieslebenite  or  Gray  Silver  Ore. — H.  2 — 2.5.  G. 
6 — 6.4.  Luster  metallic.  Color  and  streak  light 
steel-gray,  inclining  to  silver-white,  also  blackish 
lead-gray.  Yields  easily  to  the  knife,  and  is  rather 
brittle.  Fracture  uneven.  Powder  steel-gray  0  Ap- 
proximate composition ;  silver  22,  lead  30,  antimony 
28,  sulphur  18,  iron  and  copper  2%. 

Stephanite,  Brittle  or  Black  Silver.— H.  2—2.5.  G. 
6.3.  Luster  metallic.  Color,  streak  and  powder 
iron-black.  Fracture  uneven.  Approximate  composi- 
tion; silver  68.5,  antimony  15,  sulphur  16.5%o  Solu- 
ble in  heated  dilute  nitric  acid. 

Cerargyrite,  Horn  Silver  or  Chloride  of  Silver. — H. 
1 — 1.5.  G.  5.5.  When  nearly  pure,  looks  like  wax. 
Luster  resinous.  Color  pearl-gray,  grayish  green, 
whitish,  rarely  violet-blue,  sometimes  colorless  when 
perfectly  pure;  brown,  or  violet-brown  after  exposure. 
Streak  shining.  Translucent.  Sectile,  cuts  like  wax. 
Not  soluble  in  nitric  acid.  A  fragment  placed  on  a 
strip  of  zinc,  and  moistened  with  a  drop  of  water, 
swells  up,  turns  black  and  finally  is  entirely  reduced 
to  metallic  silver,  which  shows  the  metallic  luster  on 
being  pressed  with  the  point  of  a  knife.  Composition  : 
silver  75.3,  chlorine  24.7%. 

Embolite  or  Bromide  of  Silver. — H.  1 — 1.5.  G.  5.5. 
Eesembles  horn  silver.  Luster  resinous.  Color 
usually  greener  than  horn  silver,  often  dark,  becom- 
ing darker  on  exposure.  Composition :  silver  67, 
chlorine  13,  bromine  20%. 

(Besides  the  above,  there  are  some  20  other  silver 
minerals  of  small  importance  commercially.) 

PLATINUM—  Native.— H.  4—4.5.     G.  16—19.    Luster 


212         PROSPECTING  AND  VALUING  MINES. 

metallic,  not  very  bright;  color  and  streak  -whitish 
steel-gray;  shining.  Opaque.  Ductile.  Malleable. 
Occurs  usually  in  small  grains;  occasionally  in  masses 
of  several  pounds  weight.  Infusible.  Soluble  only 
in  heated  nitro-muriatic  acid. 

IRIDOSMINE — Native.' — H.  6 — 7.  G.  19 — 21.  Lus- 
ter metallic.  Color  tin-white  and  light  steel-gray. 
Opaque.  Malleable  with  difficulty.  Composition : 
the  metals  iridium  and  osmium  in  varying  propor- 
tions, in  combination  with  small  amounts  of  rhodium, 
platinum  and  ruthenium.  Occurs  as  small  flattened 
grains  in  gold  washings. 

QUICKSILVER  OR  MERCURY — Native. — G.  13.56.  Fluid. 
Luster  metallic.  Color  tin-white.  Opaque. 

Cinnabar  or  Sulphide  of  Mercury. — H.  2.  G.  9.0. 
Luster  adamantine,  inclining  to  metallic  when  dark 
colored,  and  to  dull  in  friable  varieties.  Color  cochi- 
neal-red to  brownish  red  and  lead-gray.  Streak 
scarlet;  subtransparent  to  opaque.  Fracture  uneven. 
Powder  bright  scarlet,  being  the  article  known  as  ver- 
milion. Composition:  quicksilver  86.2,  sulphur 
13.8%. 

Metacinnabarite. — A  dark  to  blackish  variety  of 
cinnabar.  H.  2.5.  G.  8.19.  Luster  metallic  to  dull. 
Color  steel-gray  or  blackish  lead-gray.  Streak  nearly 
black.  Opaque. 

There  are  a  number  of  combinations  of  mercury 
with  selenium, chlorine  and  iodine  which  are  of  small 
commercial  value. 

COPPER. — All  the  following  minerals  marked  with 
an  asterisk  (*)  are  dissolved  in  nitric  acid,  and  will 
deposit  red  metallic  copper  on  polished  iron  dipped 
into  the  solution. 

*  Native.—  H.  2.5—3.  G.  8.84.  Luster  metallic. 
Color  copper-red.  Streak  metallic  and  shining. 
Ductile  and  malleable. 

* Chalcopyrite  or  Copper  Pyrite. — H.  3.5 — 4.  G. 
4.2.  Luster  metallic.  Color  brass-yellow;  subject  to 


ORES.  213 

tarnish  and  often  iridescent.  Streak  greenish  black — 
a  little  shining.  Opaque.  Fracture  conchoidal,  un- 
even. Powder  greenish-black.  Varies  in  the  inten- 
sity of  the  yellow  color,  when  massive,  according  to 
the  amount  of  iron  pyrite  in  the  ore,  becoming  paler 
in  proportion.  It  may  be  distinguished  from  iron 
pyrite  also  by  being  much  softer  and  easily  scratched 
with  a  knife.  Composition  when  pure:  copper  34, 
iron  30,  sulphur  36%. 

*Cubanite,  a  Copper  Pyrite. — Similar  to  chalcopyrite. 
H.  4.0.  G.  4.0.  Cleavage  rather  more  distinct  than 
in  ordinary  pyrite.  Massive.  Color  between  bronze 
and  brass-yellow.  Streak  dark  reddish  bronze  to 
black.  Composition;  copper  21,  iron  39,  sulphur  39% 
with  a  little  silica. 

*Barnhardite>  a  Copper  Pyrite. — Similar  to  chalco- 
pyrite. H.  3.5.  G.  4.5.  Compact,  massive.  Luster 
metallic.  Color  bronze-yellow.  Streak  grayish 
black,  slightly  shining.  Fracture  conchoidal,  uneven. 
Brittle.  Tarnishes  easily  to  peacock  tints,  or  becom- 
ing brown.  Composition  :  copper  48,  iron  22,  sulphur 
30%. 

*Bornite,  Purple,  Variegated,  Horseflesh  or  Peacock 
Copper. — H.  3.0.  G.  4.5 — 5.5.  Massive,  structure 
granular  or  compact.  Luster  metallic.  Color  between 
copper-red  and  pinchbeck-brown;  tarnishes  easily  to 
red,  blue  and  purple  tints.  Streak  and  powder  pale 
grayish  black.  Brittle.  Easily  scratched  with  a 
knife.  Approximate  composition  :  copper  58,  iron  155 
sulphur  27%. 

*Chalcocite  or  Vitreous  Copper. — H.  2.5 — 3.0.  Go 
5.6.  Luster  metallic.  Color,  streak  and  powder 
dark  lead-gray ;  often  tarnishes  blue  or  green.  Streak 
sometimes  shining.  Resembles  some  silver  ores,  but 
gives  copper  instead  of  silver  when  heated  on  char- 
coal. Approximate  composition :  copper  78,  iron  2, 
sulphur  20%. 

* Tetrahedrite  or    Gray    Copper. — H.    3,0- — 4.5.      G. 


PROSPECTING  AND  VALUING  MINES. 

4o5 — 5.L  Luster  metallic.  Color  between  light 
flint-gray  and  iron-black.  Streak  and  powder  gen- 
erally the  same,  sometimes  inclining  to  brown  and 
cherry-red.  Opaque.  Bather  brittle.  Fracture  sub- 
conchoidal,  uneven.  This  is  a  very  complex  ore, 
carrying  not  infrequently  a  valuable  amount  of  silver. 
Ordinary  composition:  copper  30  to  40;  antimony  15 
to  25;  sulphur  20  to  25%;  with  iron,  arsenic,  zinc, 
silver,  and  sometimes  mercury.  In  forty-seven 
analyses  given  by  Dana,  the  silver  contents  range  from 
a  trace  to  17%,  and  in  one  instance  31%,  replacing 
copper  or  iron. 

*  Cuprite  or  Red  Oxide  of  Copper. — H.  3.5 — 4.0.  G. 
5.8 — 6.0.  Luster  adamantine  or  submetallic  to  earthy. 
Color  red  of  various  shades,  particularly  cochineal- 
red ;  occasionally  crimson  red  by  transmitted  light. 
Streak  and  powder  several  shades  of  brownish  red. 
Streak  shining.  Subtransparent  to  subtranslucent. 
Brittle.  Fracture  subconchoidal,  uneven.  Compo- 
sition when  pure:  copper  88.8,  oxygen  11.2%. 

*Melaconite  or  Black  Oxide  of  Copper. — H.  3.0.  G. 
6 — 6.2.  Usually  massive  or  as  an  earthy  powder. 
Luster  metallic,  and  color  steel  or  iron-gray  when  in 
thin  scales;  dull  and  earthy,  with  a  black  or  grayish 
black  color,  and  ordinarily  soiling  the  fingers  when 
massive  or  powdery.  Composition:  copper  79.85, 
oxygen  20.15%. 

* Malachite  or  Green  Carbonate  of  Copper. — H.  3.5 — 
4.  G.  3.7—4.  Luster  of  crystals  adamantine,  inclin- 
ing to  vitreous;  of  fibrous  varieties,  silky;  often  dull 
and  earthy.  Color  bright  green.  Streak  paler  green. 
From  translucent  to  opaque.  Fracture  subconchoidal, 
uneven.  About  62%  copper;  remainder  carbonic 
acid,  oxygen  and  water. 

*Azurite  or  Blue  Carbonate  of  Copper. — H.  3.5 — 4.2. 
G.  3.5 — 3.8.  Crystallized  or  massive,  also  dull  and 
earthy.  Luster  vitreous.  Color  various  shades  of 
azure  blue  passing  into  dark  blue.  Streak  blue, 


ORES. .  215 

lighter  than  the  color.  Fracture  conchoidal.  Brittle. 
Partially  translucent  when  crystallized.  About  61% 
copper,  remainder  carbonic  acid,  oxygen  and  water. 

Chrysocolla  or  Copper  Silicate. — H.  2.0 — 4.0.  G. 
2.1.  Slightly  crystalline;  often  opal-like  or  enamel- 
like  in  texture ;  earthy.  In  seams  or  crusts.  Some- 
times botryoidal.  Luster  vitreous,  shining,  earthy, 
Color  green,  bluish  green  passing  into  sky  and  tur- 
quoise-blue; brown  to  black  when  impure.  Streak 
when  pure,  white.  Translucent  to  opaque.  Rather 
sectile;  translucent  varieties  brittle.  Eesembles  the 
green  carbonate,  but  is  paler  green,  usually  has  a 
coarser  texture  (is  never  fibrous),  a  smoother  surface, 
somewhat  waxy  luster,  and  is  usually  an  incrustation 
upon  other  ores.  About  35%  copper;  remainder 
silica,  oxygen,  water  and  small  amount  of  iron  oxide. 

Ata':amite  or  Chloride  of  Copper. — H.  3.0 — 3.5.  G. 
3.7 — 4.3.  Luster  adamantine  to  vitreous.  Color  vari- 
ous shades  of  bright  green,  rather  darker  than  emerald, 
sometimes  blackish  green.  Streak  apple-green. 
Somewhat  translucent.  Composition:  about  58% 
copper;  remainder  oxygen,  chlorine  and  water. 

Chalcocite,  Sulphate  of  Copper,  Bluestone. — H.  2.5. 
G.  2.2.  Crystallized.  Luster  vitreous.  Color  shades 
of  blue  from  sky  to  darker;  sometimes  greenish  blue. 
Streak  uncolored.  Taste  metallic.  Brittle.  Sub- 
translucent.  About  38%  copper;  remainder  oxygen, 
sulphuric  acid  and  water.  Soluble  in  water. 

(In  addition  to  the  foregoing,  there  are  of  the 
rarer  copper  minerals  some  21  combinations  with  sulr 
phur  and  arsenic;  two  with  silica;  26  with  phosphoric, 
arsenious  or  sulphuric  acids;  and  tw7o  other  carbon- 
ates. They  are,  however,  only  mineral  curiosities. 
The  total  number  of  copper-bearing  minerals  is  about 
65.) 

LEAD — Native. — H.  1.5.  G.  11.44  when  pure.  Lus- 
ter metallic.  Color  lead-gray.  Malleable  and  ductile. 

Galenite,   Galena   or    Lead  Sulphide.  —  H.  2. 5,     G, 


216        PROSPECTING  AND  VALUING  MINES. 

7.2 — 7.7.  Luster  metallic.  Color  and  streak  lead- 
gray.  Surface  of  crystals  occasionally  with  bluish 
tarnisho  Fracture  flat,  subconchoidal  or  even.  Very 
brittle.  Soluble  in  nitric  acid.  Yields  lead  or  char- 
coal. Crystallizes  in  cubes.  Composition  :  lead  86.6, 
sulphur  13.4%.  The  chief  ore  of  lead;  usually  carries 
some  silver,  often  some  antimony. 

Cerussite  or  Lead  Carbonate. — H.  3.0 — 3.5.  G.  5.4 
— 6.4.  Crystallized  or  earthy.  Luster  adamantine, 
inclining  to  vitreous  or  resinous;  sometimes  pearly; 
sometimes  submetallic  if  the  colors  are  dark  or  from 
superficial  change.  Color  white,  gray,  grayish  black, 
sometimes  tinged  blue  or  green  by  traces  of  copper. 
Streak  uncolored.  Fracture  conchoidal;  very  brittle. 
Subtranslucent;  usually  opaque  when  massive.  Be- 
sults  from  the  alteration  of  galena,  which  often  forms 
the  core  of  massive  varieties.  Composition :  lead 
about  70%,  remainder  oxygen,  carbonic  acid  and 
impurities. 

Pyromorphite  or  Lead  Phosphate. — H.  3.5 — 4.0.  G. 
6.5 — 7.1;  when  containing  lime  5.0 — 6.5.  Luster 
resinous.  Color  green/yellow  and  brown,  of  differ- 
ent shades;  sometimes  wax-yellow  and  fine  orange- 
yellow;  also  grayish  white  to  milk-white.  Streak 
white,  sometimes  yellowish.  Subtranslucent.  Brit- 
tle. Fracture  subconchoidal,  uneven.  Occurs  only 
with  other  ores.  Composition :  very  variable,  con- 
taining phosphates  of  lead  and  lime,  chloride  of  lead, 
fluoride  of  lime  and  arsenic. 

Anglesite  or  Lead  Sulphate.— H.  2.75—3.  G.  6.2, 
Luster  highly  adamantine,  sometimes  inclining  to 
resinous  and  vitreous.  Color  white,  tinged  yellow, 
gray,  green  and  sometimes  blue.  Streak  uncolored. 
Transparent  to  opaque.  Fracture  conchoidal.  Very 
brittle.  Occurs  massive,  crystallized  or  stalactitic. 
Composition:  lead,  about  64%;  remainder  oxygen 
and  sulphuric  acid.  Easily  fusible. 

Massicot    or    Lead   Oxide,— H.    2.0*     GK    8,0—9,0, 


ORES.  217 

Luster  dull.  Color  between  sulphur  and  orange- 
yellow,  sometimes  reddish.  Opaque.  Massive  or 
earthy.  Composition:  lead  92.83,  oxygen  7.17. 

Minium  or  Red  Oxide  of  Lead. — H.  2.0 — 3.0.  G. 
4.6.  Powdery.  Luster  dull  or  slightly  greasy. 
Color  bright  red,  mixed  with  yellow ;  streak  orange- 
yellow,  Opaque.  Composition:  lead  90.66,  oxygen 
9.34%. 

These  oxides  do  not  yield  much  commercial  lead, 
but  are  given  as  they  often  occur  as  powdery  matter 
in  the  so-called  "chloride"  ores  of  the  miners. 

(Besides  the  above  there  are  some  40  non-cornmer- 
cial  lead  minerals,  in  which  lead  is  combined  with 
sulphur,  antimony,  chlorine  and  oxygen ;  or  with  ar- 
senious,  antirnonious,  phosphoric,  tungstic,  molybdic, 
vanadic,  sulphuric,  chromic,  selenious  and  carbonic 
acids.  Several  of  these,  such  as  the  molybdate  of 
lead  (wult'enite)  and  the  vanadate  of  lead,  are  beau- 
tiful waxy  minerals  of  various  shades  of  color  from 
lemon-yellow  to  red,  occurring  usuall3r  in  crystallized 
forms,  making  beautiful  cabinet  specimens  but  not 
otherwise  specially  valuable). 

ZINC — Smithsonite,  Drybone  or  Zinc  Carbonate. — H. 
5.0.  G.  4 — 4.4.  Occurs  crystallized,  reniform,  botry- 
oidal  or  stalactitic  and  as  incrustations;  also  granular 
and  sometimes  earthy  and  powdery.  Luster  vitreous, 
inclining  to  pearly.  Color  white,  often  grayish, 
greenish,  brownish  white,  sometimes  green  and  brown. 
Streak  white.  Brittle,  Fracture  uneven.  Approxi- 
mate composition :  zinc  52%,  remainder  oxygen  and 
carbonic  acid.  Usually  carries  small  quantities  of 
lead  and  iron. 

Calamine  or  Zinc  Silicate. — H.  4.5 — 5.0.  G.  3.5. 
Occurs  crystallized,  stalactitic,  botryoidal  and 
fibrous;  also  massive  and  granular.  Luster  vitreous. 
Color  white,  sometimes  with -a  delicate  blueish  or 
greenish  shade;  also  yellowish  to  brown.  Streak 
white.  Fracture  uneven.  Brittle.  Contains  67.5% 
oxide  of  zinc. 


218         PROSPECTING  AND  VALUING  MINES. 

(The  last  two  minerals  are  very  much  alike  in  their 
general  appearance,  but  smithsonite  is  soluble  in 
muriatic  acid,  while  calami  tie  forms  a  gelatinous  mass 
under  the  same  conditions,  and  is  soluble  in  strong 
caustic  potash.) 

Zincite  or  Red  Zinc  Oxide.— R.  4.0—4.5.  G.  5.6 
Usually  in  foliated  grains,  or  coarse  particles  and 
masses;  also  granular.  Luster  subadamantiue.  Color 
orange-yellow  to  deep  red.  Streak  orange-yellow. 
Brittle.  Fracture  uneven.  Subtransluceut.  Com- 
position: zinc  80.26,  oxygen  19.74%,  usually  contain- 
ing small  quantities  of  manganese. 

Blende,  Zincblende,  Zinc  Sulphide  or  Blackjack. 
— H.  3.5—4.0.  G.  3.9—4.2.  Luster  resinous  to 
adamantine.  Color  brown,  yellow,  black,  red,  green; 
wlaite  or  yellow  when  pure.  Streak  white  to  reddish 
brown.  Powder  nearly  white,  even  in  dark  varieties. 
Fracture  conchoidal.  Brittle.  Translucent  to 
opaque.  Crystallized  or  massive.  Composition:  zinc 
67,  sulphur  33%.  Distinctly  clearable. 

Franklinite.—lA.  5.5—6.5.  G.  5.60.  Crystallized 
and  massive,  either  granular  or  compact.  Luster 
metallic.  Color  iron-black.  Streak  dark  reddish 
browne  Opaque.  Brittle.  Fracture  conchoidal. 
Acts  slightly  on  the  magnet.  Soluble  in  muriatic 
acid.  Approximate  composition :  zinc  oxide  18, 
manganese  oxide  16,  iron  oxide  66%,  the  proportions 
of  zinc  and  manganese  varying  considerably. 

Willemite,  a  Zinc  Silicate. — H.  5.5.  G.  4.0.  Crys- 
tallized massive  or  in  grains;  sometimes  fibrous. 
Luster  resinous.  Color  whitish  or  greenish  yellow 
when  purest;  apple-green,  flesh-red,  grayish  white, 
yellowish  brown ;  often  dark  brown  when  impure. 
Streak  uncolored.  Transparent  to  opaque.  Brittle. 
About  58%  zinc;  remainder  oxygen  and  silica.  Car- 
ries small  quantities  of  iron  and  manganese. 

(Besides  the  above  there  are  some  15  other  zinc- 
bearing  minerals  of  minor  importance.) 


ORES. 

IRON — Magnetite  or  Magnetic  Iron  Ore. — H.  5.5 — 
6.5,  G.  5.18.  Luster  metallic  to  subrnetallic.  Color 
and  streak  iron-black.  Opaque.  Fracture  subcon.- 
choidal,  shining.  Brittle.  Strongly  magnetic, 
sometimes  possessing  polarity,  like  the  needle  of  a 
compass.  Composition:  iron  72.4,  oxygen  27.6%. 

Hematite  or  lied  Oxide  of  Iron,  or  Specular  Iron 
Ore. — H.  5.5 — 6.5.  G.  4.2 — 5.3.  Crystallized,  colum- 
nar, granular,  botryoidal  and  stalactitic,  as  well  as 
micaceous  and  compact.  Luster  of  crystals  me- 
tallic, sometimes  brilliantly  so;  sometimes  earthy. 
Color  dark  steel-gray  or  iron-black ;  when  earthy 
inclined  to  red.  Streak  cherry-red  or  reddish  brown. 
Opaque.  Fracture  subconchoidal,  uneven;  some- 
times slaty.  Sometimes  attractable  by  the  magnet. 
Composition  :  iron  70,  oxygen  30%.  Varies  consid- 
erably in  its  mode  of  occurrence  and  outward  appear- 
ance. When  excessively  lustrous  and  brilliant  it  is 
known  as  "specular  iron  ore;"  when  in  .thin  flakes 
and  foliated,  "micaceous  iron  ore;"  when  compact 
or  fibrous  with  a  reddish  brown  or  iron-black  color, 
"red  hematite;"  or  "clay  iron  ore"  when  mixed  with 
earthy  impurities,  and  possessing  an  earthy  appear- 
ance and  no  luster,  with  not  infrequently  a  deep  dull 
red  color. 

Limonite,  Brown  Hematite  or  Bog  Iron  Ore. — H,  5.0 
— 5.5.  G.  3.6—  4.0.  Usually  in  stalactitic  and 
botryoidal  forms,  having  a  more  or  less  fibrous  struc- 
ture; also  concretionary,  massive  and  occasionally 
earthy.  Luster  silky,  often  submetallic;  sometimes 
dull  and  earthy.  Color  of  surface  of  fracture  various 
shades  of  brown,  commonly  dark,  and  none  bright; 
sometimes  with  a  nearly  black  varnish-like  exterior; 
when  earthy,  brownish  yellow  to  yellow  ocher. 
Streak  yellowish  brown.  Composition  :  differs  from 
hematite  in  carrying  about  16%  of  water.  The  term 
"bog"  ore  is  applied  to  the  modern  formations  found 
in  marshy  places,  which  usually  conteJu  manganese  as 
an  impurity. 


220         PROSPECTING  AND  VALUING  MINE8. 

(The  three  foregoing  minerals  produce  the  bulk  of 
the  iron  of  commerce.  They  can  readily  be  distin- 
guished from  each  other  by  the  streak,  which  is 
respectively  black,  red  or  yellowish  brown.  The 
following  minerals,  while  strictly  iron  ores,  are  valu- 
able chiefly  for  their  other  constituents  such  as  zinc, 
chrome,  sulphur,  arsenic,  etc.,  and  the  precious  metals 
found  in  their  company.) 

Franklinite. — Described  with  the  zinc  minerals. 

Sidemte,  Spathic  Iron  or  Iron  Carbonate. — H.  3.5 — 
4.5.  G.  3.8.  Occurs  crystallized;  also  in  botryoidal 
and  globular  forms,  somewhat  fibrous  within,  occa- 
sionally silky.  Often  massive.  Luster  vitreous,  more 
or  less  pearly.  Color  ash-gray,  greenish  gray,  also 
brown  and  reddish  brown,  rarely  green;  sometimes 
white.  Fracture  uneven.  Brittle.  Streak  white. 
Composition:  oxide  of  iron  62.1,  carbonic  acid 
37.9%.  'Usually  carries  manganese,  magnesia  and 
lime  as  impurities.  A  sparry  looking  ore,  distinctly 
cleavable,  turning  brown  to  black  on  exposure.  A 
good  ore  of  iron  when  abundant. 

Pyrite,  Iron  Pyrite  or  Iron  Sulphide. — H.  6.0 
— 6.5.  G.  4.8 — 5.2.  Crystallized  or  massive.  Luster 
metallic,  splendent  to  glistening.  Color  a  pale 
brass-yellow  nearly  uniform.  Streak  greenish  or 
brownish  black.  Opaque.  Fracture  conchoidal, 
uneven.  Brittle.  Strikes  fire  with  steel.  Composi- 
tion (omitting  impurities):  iron  46.7,  sulphur  53.3%. 
Crystallizes  in  cubes.  The  pyrites  of  gold  regions 
usually  carry  gold,  which  may  be  occasionally  seen 
projecting  from  the  faces  of  the  crystals.  Other 
varieties  carry  small  quantities  of  nickel,  cobalt,  silver 
or  tin.  Pyrite  is  one  of  the  commonest  of  minerals, 
and  aside  from  the  precious  metals  it  contains,  is 
chiefly  used  in  the  manufacture  of  sulphuric  acid,  the 
acid  being  produced  more  cheaply  by  this  method  than 
from  sulphur  direct. 

-'— Similar  to  ordinary  pyrite  in  composi- 


ORES,  221 

tion,  but  differs  in  the  form  of  the  crystals,  which  are 
often  flat  and  crested.  H.  6.0—6.5.  G.  4.8.  Crys- 
tallized, globular  or  reniform ;  often  massive  or  gran- 
ular. Luster  metallic.  Color  pale  bronze-yellow, 
sometimes  inclined  to  green  or  gray.  Streak  grayish 
or  brownish  black.  Fracture  uneven.  Brittle.  Often 
carries  gold. 

Pyrrhotite  or  Magnetic  Iron  Pyrite. — H.  3.5 — 4.5. 
G.  4.6.  Commonly  massive  or  granular.  Luster 
metallic.  Color  between  bronze-yellow  and  copper- 
red,  and  tarnishing  easily.  Streak  dark  grayish 
black.  Brittle.  Magnetic,  being  attracted  in  fine 
powder  by  a  magnet,  when  not  affecting  a  magnetic 
needle.  This  ore  is  valuable  chiefly  for  the  nickel  it 
contains,  which  in  some  cases  ranges  from  3  to  5%, 
and  furnishes  the  bulk  of  the  nickel  of  commerce. 
Composition:  iron  60.5,  sulphur  39. 5%. 

Mispickel  or  Arsenical  Parties. — H.  5.5 — 6.0.  G. 
6.0 — 6.4.  Luster  metallic.  Color  silver-white,  in- 
clining to  steel-gray.  Streak  dark  grayish  black. 
Fracture  uneven.  Brittle.  Composition:  iron  34.4, 
sulphur  19.6,  arsenic  46.0%.  This  mineral  is  the 
source  of  the  bulk  of  the  arsenic  of  commerce,  as  well 
as  cobalt,  and  is  associated  with  and  frequently  carries 
silver  and  gold  in  small  quantities. 

llmentie  or  Titanic  Iron.—  H.  5.0—6.0.  G.  4.5—- 
5.0.  Massive  or  as  loose  grains  in  sand.  Luster 
submetallic.  Color  iron-black.  Streak  submetallic, 
powder  black  to  brownish  red.  Opaque.  Fracture 
conchoidal.  Slightly  influencing  the  magnetic 
needle.  Composition :  oxide  of  iron  with  varying 
amounts  of  titanium,  3  to  30%.  Not  a  true  iron  ore. 

(Besides  the  above  there  are  nearly  40  other  non- 
commercial iron  minerals,  consisting  of  silicates,  sul- 
phates, phosphates,  arsenates,  carbonates,  etc.) 

MANGANESE — Manganite. — H.  4.0.  G.  4.3.  Occurs 
crystallized,  stalactitic,  seldom  granular.  Luster  sub- 
metallic.  Color  dark  steel-gray  to  iron-black.  Streak 


222        PROSPECTING  AND  VALUING  MINES. 

and  powder  reddish  brown,  sometimes  nearly  black. 
Opaque.  Fracture  uneven.  Composition:  manganese 
62.5,  oxygen  27.3,  water  10.2%. 

Pyrolusite,  Manganese  Dioxide. — H.  2.0 — 2.5.  G. 
4.8,  Luster  metallic.  Color  iron-black,  dark  steel- 
gray,  sometimes  bluish.  Streak  black  or  bluish 
black,  sometimes  submetallic.  Opaque.  Bather  brit- 
tle. Composition:  manganese  63.3,  oxygen  36.7%. 
One  of  the  most  important  ores  of  manganese;  it  is 
easily  distinguished  from  psilomelane  by  its  inferior 
hardness,  and  being  usually  crystalline;  from  rnan- 
ganite,  by  the  color  of  the  streak  and  powder.  Often 
soils  the  hands. 

Psilomelane  or  Black  Manganese  Oxide. — H.  5.0 — 6.0. 
G.  3.7 — 4.7.  Occurs  massive  and  botryoidals  reniform 
and  stalactitic.  Luster  submetallic.  Color  iron- 
black,  passing  into  dark  steel-gray.  Streak  brownish 
black,  shining.  Opaque.  Composition  :  an  oxide  of 
manganese  (variable  in  quantity)  with  oxide  of  bar- 
ium, and  several  other  impurities  in  minor  quantities. 
Not  being  found  crystallized  the  exact  nature  of  the 
species  is  yet  doubtful. 

Wad  or  Bog  Manganese. — The  ores  included  under 
this  name  occur  in  amorphous  and  reniform  masses, 
either  earthy  or  compact,  and  sometimes  incrusting. 
They  are  mixtures  of  different  oxides  and  cannot  be 
considered  a  distinct  species.  H.  0.5 — 6.0.  G.  3.0 
— 4.2,  often  loosely  aggregated  and  feeling  very  light 
to  the  hand.  Color  dull  black,  bluish  or  brownish 
black.  Composition:  manganese  oxide,  with  iron, 
barium,  cobalt  and  copper  oxides  in  varying  propor- 
tions. 

(There  are,  in  addition  to  the  above,  some  20  other 
unimportant  manganese  minerals.) 

Tix—Cassiterite  or  Tin  Oxide.— H.  6.0—7.0.  G. 
6.4 — 7.1.  Occurs  crystallized  and  massive.  Luster 
adamantine,  and  crystals  usually  splendent.  Brown 
or  black;  sometimes  rod,  gray,  white  or  yellow. 


ORES..  223 

Streak  white,  grayish,  brownish.  Crystals  nearljr 
transparent,  sometimes  opaque  when  massive.  Frac- 
ture subconchoidal,  uneven.  Brittle.  Composition : 
tin  78.67,  oxygen  21.33%'.  Furnishes  the  tin  of  com- 
merce. Does  not  look  much  like  a  metallic  ore  and  is 
often  confounded  with  the  valueless  mineral  epidote. 
Only  slightly  acted  on  by  acids.  Detected  usually  by 
its  weight. 

Stream  tin  is  nothing  but  the  ore  in  the  state  of 
sand,  as  it  occurs  in  the  gravel  derived  from  the 
decomposition  of  the  rocks  carrying  the  ore. 

Wood  tin  is  an  irony-looking  mineral,  a  variety  of 
cassiterite,  very  heavy,  occurring  in  rounded,  botry- 
oidal  or  reniform  shapes,  concentric  in  structure,  and 
radiated  fibrous  internally,  although  very  compact, 
with  the  color  brownish,  and  the  rings  of  mixed  shades, 
looking  somewhat  like  dry  wood.  Occurs  in  the 
gravel  of  streams. 

Stannite  or  Tin  Sulphide. — H.  4.  G.  4.4.  Com- 
monly massive,  granulated,  or  disseminated  through 
the  rock  in  small  grains.  Luster  metallic.  Color 
steel-gray  to  iron-black,  the  former  when  pure.  Streak 
blackish.  When  copper  pyrite  is  present  in  the  ore 
the  color  is  often  yellowish.  Opaque.  Brittle.  Frac- 
ture uneven.  Composition:  tin  27.2,  copper  29.3, 
sulphur  29.6,  iron  6.5,  zinc  7.5%.  It  frequently  has 
the  appearance  of  bronze  or  bell  metal,  and  is  hence 
called  "bell  metal"  ore. 

(Tin  is  found  in  small  quantities  as  a  component  of 
several  other  ores.) 

CHROMIUM — (Jhromite  or  Chrome  Iron. — H.  5.5. 
G.  4.4.  Usually  occurs  massive;  structure  fine  gran- 
ular or  compact.  Luster  submetallic.  Streak  brown. 
Color  between  iron-black  and  brownish  black.  Opaque. 
Brittle.  Fracture  uneven.  Sometimes  magnetic. 
Composition:  oxide  of  chromium  68,  oxide  of  iron 
32%.  Usually  with  alumina  and  silica  as  impurities 
when  massive.  The  ore  has  usually  green  incrusta- 


PROSPECTING  AND  VALUING  MINES. 

tions  in  the  seams  which  distinguish  it  readily  from 
the  other  iron  ores.  Affords  the  chrome  of  commerce, 
not  being  used  as  an  iron  ore. 

(Several  other  ores  contain  chromium,  but  not  in 
available  quantities.) 

NICKEL — Pyrrhotite  or  Magnetic  Iron  Pyrite.  (See 
iron  ores). — The  chief  source  of  nickel. 

Niccolite,  Copper-nickel  or  Arsenical  Nickel. — - 
Usually  massive,  no  visible  structure;  also  reniform 
and  arborescent.  H.  5.0 — 5.5.  G.  7.5.  Luster  me- 
tallic. Color  pale  copper-red,  with  a  gray  to  blackish 
tarnish.  Streak  pale  brownish  black.  Opaque. 
Brittle.  Composition:  nickel  44.1,  arsenic  55.9%; 
sometimes  part  of  the  arsenic  is  replaced  by  antimony, 
with  small  quantities  of  lead,  cobalt  and  sulphur. 
Kesembles  pyrrhotite  or  magnetic  iron  pyrite,  but 
is  not  magnetic. 

Gersdorffite  or  Nickel  Glance — C rystallization 
cubic;  also  lamellar  and  granular  massive,  H.  5.5. 
G.  5.6 — 6.9.  Luster  metallic.  Color  silver-white  to 
steel-gray,  often  tarnished  gray  or  grayish  black. 
Streak  grayish  black.  Fracture  uneven.  Composi- 
tion:  nickel  35.1,  arsenic  45.5,  sulphur  19.4%,  with 
part  of  the  nickel  often  replaced  with  iron  or  cobalt. 
Out  of  18  analyses  the  nickel  ranges  from  19  to  40%. 

Gent/lite  or  Silicate  of  Nickel. — Not  crystallized, 
occurring  usually  as  incrustations.  H.  3.4.  G.  2.4. 
Luster  resinous.  Color  pale  apple-green  or  yellowish* 
Streak  greenish  white.  Translucent  to  opaque.  An 
unimportant  compound  of  nickel  and  silica,  often 
associated  with  chrome  iron. 

Annabergite  or  Nickel  Ocher. — In  slender  crystals; 
also  massive  and  disseminated  through  the  gangue. 
Soft.  Color  fine  apple-green.  Streak  greenish  white. 
Fracture  uneven  or  earthy.  A  compound  of  nickel 
and  arsenic.  Unimportant. 

Zaratite  or  Emerald  Nickel. — Incrusting,  also  mas- 
sive and  coraDact.  H.  3,0 — 3.2.  G,  2.6.  Lustfv: 


ORES.  225 

vitreous.  Colo*1  emerald-green.  Streak  pale  green. 
Translucent.  Brittle.  A  carbonate  of  nickel.  Unim- 
portant. 

(The  last  three  minerals,  with  several  others  of 
similar  green  color,  include  the  green  minerals  found 
in  nickel  ores,  and  which  usually  attract  the  attention 
of  the  prospector  from  their  bright  color,  resembling 
the  green  carbonate  of  copper.) 

COBALT  —  Mispickel  or  Arsenical  Pyrite.  —  (Described 
under  iron  ores). 

ISmaltite,  Smaltine  or  Cobalt  Arsenide.  —  Crystallized 
and  massive.  H.  5.5—6.0.  G.  6.4  —  7.2.  Luster 
metallic.  Color  tin-white,  inclining  when  massive  to 
steel-gray,  sometimes  iridescent  or  tarnished.  Streak 
grayish  black.  .Fracture  granular  and  uneven. 
Brittle.  Composition:  cobalt  9.4,  nickel  9.5,  iron 
9,  and  arsenic  72.1%.  In  some  varieties  the  nickel  is 
absent  and  the  cobalt  runs  up  to  23%  or  over,  replac- 
ing the  nickel  and  part  of  the  iron. 

Gobaiiite,  Cobaltine  or  Cobalt  Glance.  —  Crystallized, 
massive,  granular  and  compact.  H.  5.5.  G.  6.0  —  • 
6.3.  Luster  metallic.  Color  silver-white,  inclined  to 
red;  also  steel-gray  with  a  violet  tinge,  or  grayish 
black  when  containing  much  iron.  Streak  grayish 
black.  Fracture  uneven  and  lamellar.  Brittle.  Com- 
position :  cobalt  35.5,  arsenic  45.2,  sulphur  19.3%. 
The  cobalt  is  sometimes  largely  replaced  by  the  iron, 
in  which  case  the  percentage  may  run  down  as  low  as 


Erythrite,  Cobalt  Bloom  or  Red  Cobalt.  —  Crystal- 
lized, also  in  globular  and  reniform  shapes;  also  as 
incrustations  and  powdery.  H.  1.5  —  2.5.  G.  2.9. 
Luster  pearly  to  vitreous;  also  dull  and  earthy. 
Color  crimson  and  peach-red,  sometimes  pearl  to 
greenish  gray;  red  tints  incline  to  blue.  Streak  a 
little  paler  than  the  color;  the  dry  powder  deep 
lavender-blue.  Subtranslucent.  Sectile.  Composi- 
tion: oxide  of  cobalt  37.55,  arsenic  acid  38.43,  and 


226         PROSPECTING  AND  VALUING  MINES. 

water  24.02  %.     The  delicate   peach-red  of  this  min- 
eral is  very  characteristic. 

(The  above  are  the  chief  cobalt  ores.  There  are  a 
few  others  of  less  importance.  Cobalt  is  a  frequent 
associate  in  nickel  ores,  and  both  nickel  and  cobalt 
often  occur  in  copper  ores.) 

ANTIMONY — Stibnite,  Antimony  Sulphide,  Gray  Anti- 
mony or  Antimony  Glance. — Occurs  crystallized  or  mas- 
sive. When  massive,  not  infrequently  more  or  less 
fibrous  or  radiated.  H.  2.0.  G.  4.5.  Luster  metal- 
lic. Color  and  streak  lead-gray,  inclining  to  steel- 
gray;  liable  to  blackish  tarnish.  Fracture  small  sub- 
conchoidaL  Sectile.  Composition:  antimony  71.8, 
sulphur  28,2%.  Eesemblessorne  manganese  ores,  but 
is  distinguished  by  being  easily  fusible.  Furnishes 
the  bulk  of  the  antimony  of  commerce. 

(Native  antimony  and  the  oxides  do  not  occur  in 
quantities  to  make  them  valuable  as  ores  of  the  metal. ) 

ARSENIC — Realgar  or  Red  Sulphide  of  Arsenic. — 
Crystallized  or  granular  and  compact.  H.  1.5 — 2.0. 
G.  3,5.  Luster  resinous.  Color  aurora-red  or  orange- 
yellow.  Streak  similar.  Translucent.  Fracture  un- 
even. Composition:  arsenic  70.1,  sulphur  29.9%. 

Orpimentor  Yellow  Sulphide  of  Arsenic. — Crystallized 
or  massive.  H.  1.5.  G.  3.5.  Luster  pearly  on  the 
faces  of  cleavage,  elsewhere  resinous.  Color  several 
shades  of  lemon-yellow.  Streak  a  little  paler  than  the 
color.  Subtranslucent.  Subsectile.  Composition : 
arsenic  61,  sulphur  39%. 

(The  above  minerals  do  not  occur  in  large  quanti- 
ties. Artificially-made  orpiment  is  used  as  a  paint. 
Commercial  arsenic  is  usually  a  by-product  from  the 
working  of  mispickel  and  the  ores  of  nickel  and 
cobalt.) 

BISMUTH — Native. — Crystallized,  foliated  or  gran- 
ular. H.  2.0.-- 2.5.  G.  9.7.  Luster  metallic. 
Streak  and  color  silver-white,  with  a  reddish  hue; 
subject  to  tarnish.  Opaque.  Sectile.  Brittle  when 


ORES. 

cold,  but  somewhat  malleable  when  heated.  Very 
fusible. 

(Bismuth  occurs  in  some  dozen  combinations,  but 
usually  in  small  quantities  with  other  compounds  in 
mineral  veins.  The  native  metal  furnishes  the  bulk  o.f 
the  commercial  article.) 

TITANIUM — Entile  or  Titanium  Oxide. — Crystallized 
or  massive.  H.  6.0 — 6.5.  G.  4.2.  Luster  metallic- 
adamantine.  Color  reddish  brown,  passing  into  red ; 
sometimes  yellowish,  bluish,  violet,  black;  rarely 
grass-green.  Streak  pale  brown.  Subtransparent  to 
opaque.  Fracture  subconchoidal,  uneven.  Brittle. 
Composition :  titanium  61,  oxygen  39%. 

(Ilmenite,  titanic  iron,  etc.,  are  described  with  the 
iron  ores.) 

TUNGSTEN — Wolframite,  Tung  state  of  Iron. — Crystal- 
lized or  massive.  H.  5.0 — 5.5.  G.  7.1 — 7.5.  Lustersub- 
raetallic.  Color  dark  grayish  or  brownish  black. 
Streak  dark  reddish  brown  to  black.  Opaque.  Com- 
position :  tungstic  acid  76%,  in  combination  with  iron 
and  manganese  in  variable  quantities. 

(The  tungstates  of  lead  and  lime  are  of  minor  im- 
portance.) 

CADMIUM—  Greenockite  or  Cadmium  Sulphide. — H. 
3.0 — 3.5.  G.  4.8.  Luster  adamantine.  Color 
honey-yellow,  citron-yellow,  orange-yellow,  bronze- 
yellow.  Streak  and  powder  between  orange-yellow 
and  brick-red.  Nearly  transparent.  Composition : 
cadmium  77.7,  sulphur  22.3%. 

MOLYBDENUM — Molybdenite  or  Molybdenum  Sulphide. 
' — "Usually  foliated,  massive,  or  in  scales;  also  fine 
granular.  H.  1 — 1.5,  being  easily  impressed  by 
the  nail.  G.  4.4 — 4.8.  Luster  metallic.  Color  pure 
lead-gray.  Streak  similar  to  color,  slightly  inclined 
to  green.  Opaque.  Laminae  very  flexible,  but  not 
elastic.  Sectile,  and  almost  malleable.  Fine  gray 
mark  on  paper.  Composition:  molybdenum  59,  sul- 
phur 41%.  Eesembles  graphite,  but  is  decomposed 
b;*  nitric  acid. 


228         PROSPECTING  AND  VALUING  MINES. 

URANIUM — Uraninite,  Oxide  of  Uranium,  Pitch- 
blende.— Usually  massive  and  botryoidal;  also  in 
grains.  H.  5.5.  G.  6.4 — 8.  Luster  submetallic  to 
greasy  or  pitchlike,  and  dull.  Color  grayish,  green- 
ish, brownish,  velvet-black.  Streak  brownish  black, 
grayish,  olive  green,  a  little  shining.  Opaque.  Frac- 
ture conchoidal,  uneven. 

Autunite,  Uranium  Phosphate. — H.  2.0 — 2.5.  G. 
3.0 — 3.2.  Luster  pearly  to  subadamantine.  Color 
citron -yellow  to  sulphur-yellow.  Streak  yellowish. 
Translucent. 

Torbernite,  Uranium  Phosphate,  Copper  Uraninite — 
H.  2.0 — 2.5.  G.  3.5.  Luster  pearly  to  subadaman- 
tine. Color  emerald  and  grass-green,  and  sometimes 
leek,  apple  and  siskin-green.  Streak  somewhat  paler 
than  the  color.  Translucent.  Sectile. 

(The  above  are  usually  associated  with  silver  ores.) 

VANADIUM — Vanadinite  or  Vanadate  of  Lead. — Usu- 
ally in  implanted  globules  or  incrustations.  H. 
2.75—3.0.  G.  6.6—7.2.  Luster  of  surfaces  of  frac- 
ture resinouSo  Color  light  brownish  yellow,  straw- 
yellow,  reddish  brown.  Streak  white  or  yellowish. 
Subtranslucent  to  opaque.  Fracture  uneven0  Brittle, 


CHAPTER  XIV. 
USEFUL  EARTHY  MINERALS,   ETC. 

I. INSOLUBLE. 

THE  value  of  the  deposits  of  the  various  minerals 
grouped  under  this  heading  depends  on  the  purity  of 
the  article,  the  quantities  in  which  it  is  found,  the 
cost  of  labor  and  the  facilities  of  transportation,  de- 
fective conditions  on  any  one  of  these  points  taking 
the  deposit  out  of  the  list  of  commercially  available 
propositions,  as  the  market  value  per  pound  of  most 
of  them  is  exceedingly  low,  and  the  number  of  locali- 
ties in  which  they  are  found  proportionally  great; 
while  for  some  of  them  there  is  only  a  limited  demand. 

ASBESTOS  is  one  of  the  few  well-known  minerals, 
its  white  or  greenish  white  or  bluish  fibrous  appear- 
ance being  so  characteristic  as  to  be  familiar  to  all 
prospectors.  In  silkiness  it  may  range  from  long 
flexible  fibers  like  flax  to  brittle  earthy  masses.  It  is 
a  widely  diseminated  mineral  associated  with  rocks 
which  contain  large  quantities  of  hornblende  or 
augite,  it  being  one  of  the  products  of  the  metamor- 
phism  or  decomposition  of  these  rocks,  and  is  conse- 
quently common  among  the  hornblende-schists  and 
serpentines,  which  also  produce  chrome  iron  and  soap- 
stone,  all  three  minerals  usually  occurring  in  the  same 
locality. 

The  great  difficulty  connected  with  the  mining  of 
this  substance  is  the  large  quantity  of  material  which 


230         PROSPECTING  AND   VALUING  MINES. 

must  be  handled  to  secure  any  quantity  of  asbestos, 
as  it  usually  occurs  in  small  threads,  stringers,  seams 
or  pockets,  irregularly  scattered  through  the  contain- 
ing rock,  so  that  it  must  be  worked  in  open  quarries, 
and  the  asbestos  sorted  by  hand  from  the  rock.  It 
varies  greatly  in  character,  from  short  earthy  fibers 
which  are  brittle  and  separate  with  difficulty,  the 
structure  running  across  the  seam  and  not  parallel  to 
it,  up  to  long  fine  silky  threads  of  a  pearly  white  color 
very  much  resembling  flax.  The  term  "amianthus" 
is  applied  to  this  last  variety.  The  longer  and  more 
flexible  the  fiber,  the  more  valuable  the  mineral. 
Asbestos  is  infusible,  but  the  common  notion  that 
articles  made  of  it  can  be  thrown  into  the  fire  and  thus 
cleansed  of  accumulated  dirt,  is  erroneous,  as  at  a  red 
heat  the  fibers  lose  their  flexibility  and  become  brittle. 

It  is  used  in  the  making  of  fireproof  paints,  roofing, 
piston  packing,  valve  packing,  covering  steam  pipes 
and  boilers,  fireproof  cement,  sheet  and  rolled  mill- 
board, flooring  felt,  textile  fabrics,  etc.,  being  often 
used  in  combination  with  hair  felts  and  other  sub- 
stances. It  derives  its  value  for  these  purposes  from 
its  indestructibilitj7  in  ordinary  fires,  and  the  resist- 
ance it  offers  to  the  radiation  of  heat,  a  property  which 
it  possesses  in  common  with  wool,  cotton,  feathers 
and  other  substances  which  cannot  be  safely  used  in 
the  presence  of  high  temperatures.  For  fireproof 
paints  the  length  of  the  fiber  is  not  essential,  but  is  a 
desirable  quality  for  packings  and  the  covering  of 
steam  pipes  and  boilers,  while  it  is  essential  in  all 
textile  fabrics. 

Asbestos  being  associated  with  well-marked  belts  of 
rock  the  prospector  should  familiarize  himself  with 
the  character  and  appearance  of  these  rocks  at  any 
locality  where  he  may  find  asbestos,  and  having  done 
so,  trace  this  belt  along  the  mountain  range,  as  it  will 
be  comparatively  useless  to  spend  time  on  the  rock 
strata  which  lie  either  above  or  below  it,  excepting  so 


USEFUL  EARTHY  MINERALS.  231 

far  as  they  may  help  him  to  locate  the  position  of  the 
asbestos  belt,  where  it  is  covered  up  by  earth  or  debris^ 
or  not  otherwise  traceable. 

ASPHALTUM. — Amorphous  or  without  crystalline 
structure.  G.  1 — 1.8,  sometimes  higher  from  im- 
purities. Luster  like  that  of  black  pitch.  Color 
brownish  black  and  black.  Odor  bituminous.  Melts 
usually  at  about  194°  to  212°,  and  burns  with  a  bright 
flame.  The  more  solid  kinds  graduate  into  mineral  tar, 
and  through  this  there  is  a  gradation  to  petroleum. 
Asphaltum  appears  to  be  a  residual  deposit,  derived 
from  the  evaporation  of  petroleum  products.  In  the 
United  States  fche  production  is  confined  to  the  West- 
ern States,  the  deposits  (which  are  always  found  on 
the  surface  or  near  it)  occurring  in  California,  Utah 
and  Colorado,  being  either  fairly  pure  or  mixed  with 
earthy  matter.  The  principal  source  of  foreign  supply 
is  the  island  of  Trinidad  in  the  West  Indies,  where,  at 
a  place  called  La  Brea,  there  occurs  an  asphalt  lake  of 
about  100  acres  in  extent,  the  product  of  which  is 
shipped  to  Europe  and  the  Atlantic  seaboard  of  the 
United  States.  In  Europe  a  limestone,  naturally  and 
evenly  impregnated  with  bitumen  (or  asphalt),  is 
largely  used  with  good  results, 

It  is  used  for  many  purposes  where  a  surface  imper- 
meable to  water  is  required,  combined  with  toughness. 
Natural  asphalt  rock,  and  asphaltum  in  combination 
with  other  materials,  are  used  in  the  surfacing  of 
streets  and  sidewalks,  and  the  finishing  of  roofs. 
Asphaltum  makes  a  durable  coating  for  water-pipes. 

BARYTES. — This  mineral,  also  called  "heavy  spar," 
because  of  its  great  weight,  is  a  sulphate  of  barium. 
Its  specific  gravity  is  about  4.5,  while  that  of  lime- 
stone is  only  2.5.  It  is  an  earthy  mineral  resembling 
limestone,  ranging  in  color  from  white  through  shades 
of  yellow,  gray,  red  and  brown  to  dark  brown,  accord- 
ing to  the  amount  of  impurities  present,  but  when 
crystallized  has  a  vitreous  or  glassy  luster  and  a  white 


232         PROSPECTING  AND   VALUING  MINES. 

streak  when  scratched.  Some  samples  when  rubbed 
give  off  a  fetid  odor.  It  is  not  affected  by  acids,  and 
may  thus  be  readily  distinguished  from  the  limestones 
with  which  it  may  be  associated,  as  well  as  by  its 
weight,  which  is  much  greater  than  any  of  the  similar 
minerals,  such  as  gypsum  and  carbonate  of  magnesia. 

It  occurs  in  veins  and  beds  associated  with  lime- 
stones, sandstones  and  trap  rocks,  and  not  infrequently 
forms  the  gangue,  wholly  or  in  part,  of  metallic  veins, 
especially  those  of  lead.  The  mineral  is  widely  dis- 
tributed, occurring  in  beds  in  sandstones  in  Connecti- 
cut, and  at  Isle  Royal,  Lake  Superior;  in  beds  in  lime- 
stone in  Iowa  and  New  York;  and  in  limestone  and 
associated  with  lead  ores  in  Missouri,  North  Carolina, 
Tennessee  and  Virginia.  On  the  northern  shores  of 
Lake  Superior  veins  occur  in  trap  rocks. 

Barytes  is  used  very  extensively  in  the  arts,  but 
almost  altogether  for  purposes  of  adulteration,  for 
which  its  leading  use  (about  90%)  is  in  replacing  to  a 
greater  or  less  extent  white  lead  in  paint.  The  claim 
is  made  that  a  mixture  of  one-third  white  lead,  one- 
third  oxide  of  zinc  and  one-third  ' 'floated "  barytes 
makes  a  better  paint  than  pure  white  lead.  It  is  also 
employed  as  a  "filling"  for  general  purposes,  in  pulps 
and  in  making  putty  and  pottery.  The  value  of 
ground  barytes  being  not  much  over  one  cent  per 
pound  it  is  evident  that  only  the  purer  deposits  and 
those  best  located  for  dressing  and  transportation  can 
be  made  available.  It  must  be  free  from  grains  of 
quartz,  iron  rust  and  other  impurities,  and  of  a  good 
white  color. 

BAUXITE. — G.  2.5.  Color  whitish,  grayish  to  yel- 
low ocher,  brown  and  red.  Occurs  in  round  concre- 
tionary disseminated  grains;  also  massive  oolitic; 
and  earthy,  clay-like.  Bauxite  occurs  in  the  United 
States  in  the  Coosa  Valley,  Georgia  and  Alabama,  in 
clay  beds  along  the  line  of  an  extensive  fault  in  lime- 
stone rocks,  the  beds  having  apparently  accumulated 


USEFUL  EARTH  T  MINERALS.  233 

in  depressions  eroded  along  this  fault,  no  eruptive 
rocks  being  present;  also  in  Arkansas,  in  regularly 
stratified  beds  near  the  contact  with  eruptive  rocks, 
and  in  France  as  a  residual  deposit  from  the  decay  of 
basaltic  rocks.  In  Styria,  a  deposit  12  ft.  thick  occurs 
at  the  junction  of  theTriassic  and  Jurassic  formations. 
The  favorite  associations  appear  to  be  limestone  and 
eruptive  rocks. 

From  the  large  amount  of  alumina  present  in  bauxite 
it  forms  a  valuable  source  of  aluminum,  and  the  purer 
varieties  are  largely  used  in  the  production  of  that 
metal,  being  known  as  "aluminum  ore.  "  On  the  Con- 
tinent of  Europe  the  product  of  the  quarries  at  Baux 
in  France,  from  which  the  mineral  takes  its  name,  is 
also  used  as  a  flux  in  iron  smelting. 

It  is  difficult  to  give  a  concise  description  of  this 
valuable  ore,  but  the  following  extracts  from  "Mineral 
Industry,"  Vcjl.  II.,  will  probably  be  sufficient  to  call 
attention  to  its  chief  peculiarities,  and  to  suggest  the 
desirability  of  submitting  suspected  samples  to 
analysis:  "Bauxite  has  few  specially  distinctive  char- 
acters except  its  usual  pisolitic  (pea-like)  or  concre- 
tionary character,  which  perhaps  accounts  for  its  hav- 
ing been  so  long  overlooked,  and  for  the  comparatively 
few  localities  where  it  is  known  to  occur.  The  red 
variety  of  bauxite  was  thought  to  be  pisolitic  iron  ore 
until  its  true  character  was  shown  by  analysis. 

"Bauxite  is  usually  a  concretionary  or  pisolitic  min- 
eral, though  sometimes  it  is  a  hard,  compact,  homo- 
geneous, fine-grained  rock,  commonly  oolitic  (made 
up  of  round  egg-like  fragments),  and  sometimes  an 
earthy,  clay-like  material.  It  may  therefore  be  hard, 
or  soft  and  friable,  compact  or  porous,  but  the  best 
grades  are  hard  and  have  a  metallic  ring.  The  con- 
cretions vary  in  size  from  small  peas  to  large  bowlders, 
which  are  cemented  together  by  fine-grained  hard 
bauxite,  bauxite  clay  or  silicious  material.  In  nearly 
every  case,  however,  the  concretions  or  nodules  are 


234         PROSPECTING  AND   VALUING  MINES. 

better  mineral  than  the  cementing  material.  The  con- 
cretions, also,  are  usually  harder  than  the  cementing 
material,  especially  in  the  surface  ores. 

"On  the  surface,  bauxite  beds  are  generally  marked 
by  hard,  rough  bowlders  or  loose  nodules  and  pebbles 
in  the  top  soil.  Below  the  surface,  however,  the  nod- 
ular and  pebbly  ores  are  often  comparatively  soft  and 
crumbly,  and  the  compact  oolitic  and  line-grained  ores 
-are  sometimes  a  soft  powder. 

"Bauxite  varies  in  color  from  almost  pure  white  to 
a  deep  red  or  black.  It  is  also  of  cream  and  pearl- 
white  color,  grayish,  yellowish,  amber,  pinkish, 
and  speckled  or  mottled.  .  .  .  These  colors  often 
shade  into  one  another,  sometimes  suddenly  and  some- 
times gradually,  and  it  is  seldom,  if  ever,  that  a  bank 
or  deposit  is  wholly  or  uniform!}"  of  one  color." 

CLAYS  are  essentially  silicates  of  alumina  with 
combined  water  (hydrated  aluminum  silicates),  but 
vary  immensely  in  composition,  not  only  from  differ- 
ences in  the  amount  of  silica  and  alumina  present,  but 
also  from  the  presence  of  impurities  such  as  lime, 
soda,  potash,  sand,  magnesia  and  iron  oxides  which 
affect  the  fusibility  of  the  mass.  It  is  these  differences 
which  render  "them  suitable  for  different  purposes, 
For  commercial  use  they  may  be  classed  as  fire  clays, 
pottery  and  kaolin  clays  and  brick  clays. 

Fire  Clay. — The  presence  of  alkaline  matter  andiron 
oxides  tend  to  promote  vitrification,  and  an  excess  of 
alumina  causes  shrinkage  in  burning,  so  that  a  good  fire 
clay  should  consist  practically  of  silica  and  alumina, 
with  the  smallest  amount  possible  of  iron  and  alkali,  it 
being  possible  to  counteract  the  contractibility  or 
shrinkage  by  the  addition  of  quartz  sand.  The  pres- 
ence of  an  excess  of  alumina,  however,  renders  the  clay 
more  tenacious  and  plastic,  but  this  is  not  essential  in 
a  firebrick,  though  desirable  in  pottery  clays.  The 
following  table  shows  the  relative  composition  of  five 
English  fire  clays  and  14  American  samples: 


USEFUL  EARTHY  MINERALS. 

ANALYSES  OF  FIRE  CLAYS. 


235 


a 

| 

jj 

'55 

| 

§ 

<D 

•rt 

"3 

ca 

a5 

c/5 

1 

ld 

^ 

1 

1 

English  

66*80 

21*70 

6  66 

2  60 

1  29 

0  32 

0  49 

American 

48  38 

38  81 

15  29 

1  19 

0  68 

0  06 

0  02 

The  English  examples  are  all  from  the  older  coal 
measures  and  show  as  compared  with  more  recent 
clays  a  much  less  percentage  of  alumina;  the  American 
samples  are  from  the  clay  deposits  of  New  Jersey, 
Pennsylvania,  Maryland,  Illinois  and  Missouri.  The 
great  essential  in  fire  clays  is  that  they  should  not  con- 
tain over  4%  of  impurities. 

Brick  Clays. — From  the  most  refractory  all  grades 
occur  to  those  which  fuse  or  vitrify  with  the  greatest 
ease,  and  the  adaptability  of  any  deposit  to  a  special 
purpose  is  best  determined  by  trial,  it  being,  how- 
ever, important,  if  the  bed  is  to  be  worked  on  a  large 
scale,  to  ascertain  if  its  composition  is  uniform 
throughout.  For  brickmaking,  the  presence  of  lime 
is  a  detriment,  as  if  insufficiently  ground  the  nodules 
of  lime,  having  been  converted  into  quicklime  while 
burning,  will  afterward  absorb  water,  expand  in  the 
process  and  crack  the  brick. 

Pottery  Clays. — Kaolin,  which  when  pure  is  com- 
posed of  silica  46.3,  alumina  39.8  and  water  13.9%,  is 
the  result  of  the  decomposition  of  the  feldspars  in 
granite  rocks  and  porphyries,  and  furnishes  the  mate- 
rial for  the  finer  grades  of  chinaware  and  porcelain, 
after  a  thorough  preparation  by  washing  and  settling, 
until  the  residue  is  an  impalpable  creamy  paste.  Very 
large  areas  of  these  rocks,  in  some  localities,  have  been 
thus  decomposed;  but  the  presence  of  an  excess  of 
iron  oxides,  which  would  color  the  finished  product, 


236        PROSPECTING  AND   VALUING  MINES. 

or  other  impurities,  render  the  bulk  of  them  suitable 
only  for  inferior  grades  of  china  ware. 

CORUNDUM  AND  EMERY. — "H.  9.  G.  3  to  4.1.  When 
crystallized  the  luster  is  vitreous;  color  bine,  red, 
yellow,  brown,  gray  and  nearly  white;  streak  un 
colored.  Transparent  to  translucent.  Fracture  con- 
choidal,  uneven.  Exceedingly  tough  when  com- 
pact/' (Dana.)  "These  substances  (corundum  or 
sapphire  and  emery),  so  nearly  allied  mineralog- 
ically,  are  sharply  distinguished  in  the  trade.  Min- 
eralogically  the  former  is  a  nearly  pure  alumina,  while 
the  latter  contains  a  large  proportion,  from  20  to  33%, 
of  iron  oxide.  The  trade  distinctions  are  somewhat 
as  follows :  Emery  is  always  black,  while  corundum 
is  of  various  colors,  though  more  frequently  gray  and 
never  black.  It  is  much  harder  than  emery  (taking 
the  sapphire  at  100,  Dana  gives  the  abrasive  power  of 
corundum  at  62  and  emery  46)  and  sharper,  cuts 
deeper  and  more  rapidly,  but  is  on  the  other  hand 
more  brittle  and  consequently  less  durable/'  (Gan- 
nett.) These  minerals  are  associated  with  crystalline 
rocks  such  as  granular  limestone,  gneiss,  granite,  mica 
and  chlorite  schists.  The  emery  of  Asia  Minor  occurs 
in  granular  limestone.  All  of  the  corundum  used  in 
the  United  States  is  of  domestic  production,  from 
localities  in  the  Appalachian  range,  extending  from 
Maine  to  Georgia,  and  from  some  western  points  as 
Colorado  and  other  States;  but  these  latter  are  recent 
developments,  and  as  yet  comparatively  small  pro- 
ducers. Both  corundum  and  emery  are  chiefly  used 
for  grinding  and  polishing  metals  and  other  hard  sub- 
stances. 

CRYOLITE. — "H.  2.5.  G.  2.95.  Luster  vitreous 
or  glassy ;  slightly  pearly  on  some  faces  of  the  crys- 
tals. Colors  now  white,  sometimes  reddish  or  brown- 
ish to  brick-red  and  even  black.  Subtransparent; 
immersion  in  water  increases  the  transparency. 
Brittle.  Fusible  in  the  flame  of  a  candle.  Occurs 


USEFUL  EARTHY  MINERALS.  237 

sparingly  in  the  crystal  beds  near  Pike's  Peak,  Colo.; 
but  is  a  rare  mineral  in  the  United  States.  The  prin- 
cipal foreign  locality  is  at  Evigtok,  in  West  Green- 
land, where  it  constitutes  a  large  bed  or  vein  in 
gneiss,  and  contains  galena,  zincblende,  carbonate  of 
iron,  iron  pyrite,  arsenical  pyrite,  fluorspar,  tin  ore 
and  colurntite,  all  of  them  frequently  in  tine  crystals. 
Taylor  states  that  the  cryolite  is  not  white,  except 
within  10  to  15  ft.  of  the  surface,  and  that  below  this 
it  becomes  dark-colored  and  even  black.  The  con- 
tained ores  and  other  minerals  are  most  abundant  near 
the  junction  with  the  gneiss." 

Cryolite  is  a  compound  of  fluorine,  alumina  and 
soda,  and  is  used  in  the  manufacture  of  the  latter 
article,  and  also  in  the  production  of  aluminum  (along 
with  bauxite),  as  well  as  an  ingredient  of  a  white, 
porcelain-like  glass.  The  main  supply  is  at  present 
derived  from  the  Greenland  deposits. 

FLUORSPAR. — H.  4.  Specific  gravity  3.2.  Streak 
white.  Fluorspar  is  a  glassy-looking  mineral, 
nearly  transparent  when  pale  in  color,  which  crystal- 
lizes in  square  cubes.  In  color  it  has  a  wide  range, 
varying  from  white  to  yellow,  green,  blue,  violet  and 
red,  the  commonest  colors  being  white,  pale  green  and 
violet.  The  green  varieties  look  very  much  like  bottle 
glass.  When  crystallized,  the  specimens  are  very 
beautiful.  It  occurs  in  veins  either  by  itself  or  as  the 
gangue  of  lead  ores,  and  as  beds  or  masses  in  lime- 
stones, and  is  found  in  varying  quantities  in  almost 
every  State  of  the  Union,  but  not  very  frequently  in 
workable  quantities.  While  apparently  preferably 
found  associated  with  limestones,  it  also  occurs  in 
veins  in  granite,  gneiss,  sandstones  and  slates,  and  as 
a  component  of  such  rocks  as  rhyolite.  Fluorspar  is 
used  as  a  flux  in  some  lead  and  copper  smelting  opera- 
tions, in  the  manufacture  of  hydrofluoric  acid  for  etch- 
ing on  glass  and  seals,  as  a  glaze  for  pottery,  and  in  the 
production  of  aluminum. 


238         PROSPECTING  AND  VALUING  MINES. 

GRAPHITE  OR  PLUMBAGO  (also  often  called  "black- 
lead"). — A  soft  steel-gray  to  black  mineral  with  a  me- 
tallic luster,  and  greasy  feel;  opaque;  streak  black  and 
shining;  can  be  easily  cut  with  a  knife  and  soils  the 
fingers  in  handling.  It  is  nearly  pure  carbon  (con- 
taining no  lead  as  the  common  name  might  imply)  and 
resembles  no  other  mineral  except  molybdenite,  which 
is  lustrous  lead-gray  in  color,  with  a  streak  inclining 
to  gray,  and  marks  paper  gray  instead  of  the  pure 
black  of  graphite.  Graphite  occurs  in  veins,  beds, 
and  disseminated  in  fine  particles  through  some 
schistose  rocks,  called  graphitic  schists.  It  is  con- 
fined to  the  older  rocks,  but  is  a  widely  disseminated 
mineral.  The  veins  are  true  fissures  in  gneissoid  and 
eruptive  rocks.  The  veins  produce  the  soft  crystalline 
and  foliated  forms,  which  are  the  purest  and  most 
valuable.  Graphite  also  occurs  in  beds,  but  is  usually 
more  or  less  contaminated  with  impurities,  and  less 
valuable  commercially,  the  ores  generally  being  of 
such  a  character  that  purification  is  impossible.  The 
graphitic  schists  which  are  found  in  the  same  regions 
as  the  veins  are  metamorphosed  sandstones  or  slates 
with  foliated  graphite  very  evenly  distributed  through 
the  mass  in  small  flakes,  giving  a  deep  black  color  to 
many  of  the  slates.  The  localities  where  graphite 
occurs  in  more  or  less  quantity  are  very  numerous, 
but  from  this  fact  it  is  only  those  which  produce  the 
very  best  kinds  which  have  any  commercial  value. 

American  graphites  come  into  competition  with 
those  of  Canada  and  Ceylon.  In  the  latter  island  the 
mineral  occurs  in  veins  of  immense  size  and  great 
purity  and  is  shipped  without  any  preparation  except 
sizing.  Graphite  is  used  in  the  manufacture  of  cru- 
cibles, stove-polish,  lubricating  compounds,  foundr3T- 
faciugs,  lead  pencils,  packing,  paint  and  electrical 
supplies,  and  also  in  electrotyping,  etc.  The  first 
three  industries  consume  75%  of  the  production,  the 
consumption  for  pencils  being  only  about  3%. 


USEFUL  EARTHY  MINERALS.  239 

GYPSUM  (SULPHATE  OF  LIME). — H.  1.5 — 2.0.  G. 
2.3  for  pure  crystals.  Luster  shiny,  pearly  to 
vitreous.  Massive  varieties  often  glistening,  some- 
times dull,  earthy.  Color  usually  white,  sometimes 
gray,  flesh-red,  honey-yellow,  ocher-yellow,  blue ;  im- 
pure varieties  often  black,  brown, red  or  reddish  brown. 
Streak  white.  Transparent  to  opaque.  In  addition  to 
the  above  characters  it  may  be  mentioned  that  the  crys- 
tals are  flat  or  tubular,  and  that  the  crystallized  varie- 
ties known  as  selenite  split  readily  into  thin  trans- 
parent sheets  which  are  flexible,  but  not  elastic;  and 
that  when  burned  it  forms  plaster  of  paris,  which 
hardens  promptly  on  being  mixed  with  water,  thus 
differing  from  ordinary  limestones,  which  also  require 
a  much  higher  temperature  in  burning. 

Gypsum  in  one  or  other  of  its  forms  is  found  in 
large  quantities  in  most  of  the  States  of  the  Union,  in 
connection  with  deposits  of  rock  salt,  being  impreg- 
nated with  sulphur.  The  association  with  rock  salt  is 
due  to  the  fact  that  gypsum  is  a  product  of  the  evapora- 
tion of  sea  water;  as  well  as  a  product  of  lime-bearing 
minerals  under  the  action  of  decaying  iron  pyrite. 
This  latter  action  explains  its  presence  in  vein  matter 
and  in  clajr  beds  in  a  crystallized  form.  "The  name 
plaster  of  paris  is  in  allusion  to  the  large  production 
of  that  article  at  the  gypsum  beds  of  Montmartre  near 
Paris,  which  are  mined  on  a  very  extensive  scale. 
"Selenite"  is  the  term  applied  to  the  transparent  crys- 
tallized varieties;  when  silky  and  fibrous  it  is  known 
as  "satin  spar;"  fine-grained  varieties,  delicately 
tinted  and  suitable  for  the  manufacture  of  ornaments, 
are  known  as  alabaster  or  onyx,  the  latter  term  being 
erroneously  employed.  "The  principal  use  to  which 
gypsum  is  devoted  is  an  agricultural  one.  The 
ground  rock,  or  land  plaster,  is  applied  as  a  top  dress- 
ing to  the  soil;  and  although  it  does  not  enter  directly 
to  any  extent  into  the  composition  of  plants,  it  has 
still  an  extremely  beneficial  action  upon  plant  life  and 


240         PROSPECTING  AND   VALUING  MINES. 

growth,  from  the  chemical  changes  which  it  induces 
in  the  soil.  Stucco,  plaster  of  paris,  or  calcined  gyp- 
sum, is  used  for  making  cornices,  friezes  and  other 
forms  of  interior  decorations,  the  finishing  of  walls, 
etc.  The  finer  grades  are  used  in  taking  casts  of 
natural  objects,  making  models,  etc." 

INFUSORIAL  EARTH,  tripoli,  or  mountain  meal,  consists 
entirely  when  pure  of  the  silicious  skeletons  of  micro- 
scopic vegetable  organisms  called  diatoms,  and  in  this 
respect  differs  from  chalk,  which  is  similarly  made  up 
of  the  infinitely  minute  shells  of  animal  organisms 
called  foraminifera,  but  which  are  composed  of  lime 
instead  of  silica,  and  consequently  effervesce  when 
treated  with  acids,  which  is  not  the  case  with  infuso- 
rial earths.  Deposits  of  infusorial  earth  often  cover 
many  square  miles  and  may  be  pure  white  and  chalky 
in  appearance,  like  the  deposit  at  Eed  Mountain,  north 
of  Virginia  City,  Nev.,  the  origin  of  which  must  be 
of  comparatively  recent  date,  geologically  speaking, 
as  the  writer  has  found  in  it  remains  of  insects  now 
living  in  the  neighborhood;  the  deposit  at  Santa 
Fiora,  Tuscany,  consists  of  a  grayish  white,  loose, 
earthy  meal,  and  similar  material  is  also  found  in 
Spain.  Tripoli,  or  polishing  slate,  is  a  fragile,  slaty 
or  thinly  laminated  variety,  often  much  mixed  with 
impurities  such  as  clay,  magnesia,  etc.  Other  consid- 
erable deposits  of  differing  character  are  found  in 
Nevada  and  California.  Infusorial  earth  was  at  one 
time  largely  used  as  an  absorbent  in  the  manufacture 
of  giant  powder,  but  has  given  place  to  wood  pulp  of 
late  years,  and  is  now  used  almost  exclusively  to  give 
body  to  soap,  and  as  a  polishing  powder.  The  Ked 
Mountain  deposit  is  simply  pulverized  and  put  on  the 
market  under  the  name  of  electro-silicon,  being  an  ex- 
ceptionally pure  article  of  silica,  showing  less  than 
half  of  1%  of  impurities.  The  demand  is  limited. 

The  harder,  compact  varieties,  such  as  that  found  in 
Newton  County,  Mo.,  are  quarried  and  shaped  into 
water  filters,  which  are  of  excellent  quality. 


USEFUL  EARTHY  MINERALS.  241 

LIMESTONE,  in  its  various  forms  of  ordinary  stone  or 
marble  is  too  well  known  to  need  further  description, 
and  is  found  abundantly  in  all  the  States  of  the  Union. 
The  production  of  quicklime  for  building  purposes 
amounts  to  over  60,000,000  bbl.  of  200  Ib.  each, 
involving  the  quarrying  of  over  12,000,000  tons  of  rock. 
This  does  not  include  that  mined  as  flux  for  smelting 
operations,  or  quarried  as  building  stone.  Provided 
the  lime  is  free  from  iron  in  appreciable  quantities  the 
color  is  of  little  consequence  to  the  burner,  as  it  dis- 
appears under  the  action  of  heat,  and  the  product  of 
blue  limestone  and  white  marble  are  not  to  be  distin- 
guished from  each  other.  The  presence  of  iron  is 
objectionable,  as  it  would  rust  in  the  mortar  and  when 
leached  out  by  rain  would  stain  the  building.  Mag- 
nesian  limestones,  or  dolomite,  have  usually  tinges  of 
yellow,  buff  or  drab,  instead  of  tending  to  blue  tints, 
and  are  used  in  the  manufacture  of  hydraulic  or  quick 
setting  cements.  The  value  of  marble  depends  largely 
on  the  fineness  of  the  grain  and  the  purity,  beauty  or 
peculiarity  of  the  coloring,  but  with  all  the  good  qual- 
ities at  a  maximum  the  deposit  may  be  valueless  if 
unfortunately  situated  as  regards  cheap  transporta- 
tion. 

It  is  desirable  that  limestones  used  as  flux  for  iron 
smelting  should  be  free  from  phosphorus,  just  as  the 
same  quality  is  desirable  in  the  fuel,  because  nearly 
the  whole  of  the  phosphorus  present,  both  in  the  ore, 
fuel  and  flux,  will  be  concentrated  in  the  pig  iron 
produced,  decreasing  its  value  materially  and  render- 
ing it  totally  unfitted  for  many  purposes,  especially 
the  production  of  Bessemer  steel,  which  requires  a 
practical  absence  of  phosphorus  in  all  the  material 
which  goes  into  the  blast  furnace. 

Impurities  in  the  limestone  used  for  making  quick- 
lime, especially  silica  and  alumina,  have  a  tendency  to 
vitrify,  or  melt  into  more  or  less  glassy  particles,  dur- 
ing the  process  of  burning,  and  the  product  does  not 


PROSPECTING  AND   VALUING  MINES. 

slake  into  as  smooth  a  paste  as  that  produced  from 
purer  rocks,  but  these  "poor"  limes  are  said  to  make 
a  mortar  which  is  able  to  resist  the  destructive  action 
of  atmospheric  agencies  better  than  the  "rich"  ones, 
being  apparently  less  soluble  in  rain  water. 

Limestone  is  so  abundant  a  material  in  nature  that 
we  need  in  this  place  call  attention  only  to  one  par- 
ticular variety,  used  for  lithographic  purposes.  There 
is  no  absolute  chemical  composition,  analyses  showing 
a  varying  amount  of  carbonate  of  magnesium  (2.50  to 
17.32%)  along  with  the  carbonate  of  lime  and  various 
small  quantities  of  other  substances.  The  stones  in  use 
are  usually  shades  of  drab  or  gray,  and  they  must  be 
absolutely  of  uniform  composition  throughout,  some- 
what porous  and  soft  enough  to  work  easily  under  the 
engraver's  tool,  but  tough  enough  to  bear  consider- 
able pressure  in  the  printing  press.  Such  a  stone  will 
be  very  fine-grained  and  break  with  a  shell-like  (con- 
choidal)  fracture.  Only  actual  trial  will  prove  the 
suitability  of  a  particular  stone,but  localities  which  can 
produce  good  stones  of  large  size,  say  40  by  60  in.,  are 
extremely  valuable. 

MAGNESITE  is  a  carbonate  of  magnesium,  white  in 
color  when  pure,  but  shading  into  brown  when  iron  is 
present.  It  is  moderately  hard,  tough,  and  breaks 
with  flat  conchoidal  surfaces,  and  is  somewhat  heavier 
than  quartz.  It  looks  something  like  limestone,  but 
is  only  feebly  acted  on  by  cold  acids,  though  when 
powdered  it  dissolves  readibT  in  warm  muriatic  acid 
with  effervescence.  It  is  usually  found  in  connection 
with  serpentine  rocks,  talcose  schists,  and  consequently 
with  soapstone  and  asbestos,  all  of  which  are  magne- 
sian  products.  The  ore  is  used  chiefly  in  the  manu- 
facture of  paper  from  wood  pulp,  and  as  a  refractory 
lining  for  furnaces  using  the  basic  process  for  steel 
making. 

MICA  ranges  in  color  from  white  and  very  pale 
greenish  and  brownish  shades  through  dark  brown  to 


USEFUL  EARTHY  MINERALS.  243 

black.  It  splits  easily  into  very  thin  sheets,  some- 
times as  many  as  160  to  the  inch,  which  in  the  paler 
colored  varieties  are  transparent,  but  only  partially  so 
in  the  dark  ones.  These  thin  plates  or  larninse  are 
flexible  and  not  easily  fusible,  and  in  this  respect 
differ  from  crystallized  gypsum  or  sulphate  of  lime, 
which  while  separating  into  very  thin  flakes  is  not 
flexible,  and  when  heated  crumbles  into  a  fine  powder, 
the  plaster  of  paris  of  commerce.  The  two  are  often 
mistaken  for  each  other  and  confounded  under  the 
common  name  of  "isinglass,"  which  is  really  fish  glue 
or  a  compound  prepared  from  gelatine,  and  an  organic 
product.  When  scratched  or  crushed  the  result  is  a 
whitish  powder  even  in  the  case  of  the  dark  varieties. 
Mica  is  a  common  constituent  of  granite, 
gneissic  and  schistose  rocks,  and  is  found  in  many 
localities  in  crystals  of  larger  .size  than  those  usually 
forming  an  essential  ingredient  of  the  rocks 
mentioned.  Such  crystals  have  been  reported  from 
North  Carolina  and  the  other  South  Atlantic  States; 
Maine,  New  Hampshire,  Pennsylvania,  South  Dakota, 
New  Mexico,  Wyoming,  California  and  elsewhere.  It 
has  been  found  in  almost  all  the  Pacific  States  but  not 
in  workable  quantities  of  good  quality.  South  Dakota 
has  produced  plates  12  by  18  in.  in  size  from  a  vein 
which  is  said  to  be  14  ft.  wide,  and  to  consist  of  a 
central  mass  of  feldspar  and  porphyry,  with  a  casing 
of  mica,  which  varies  in  width  from  3  to  4  ft.,  on  each 
side.  The  country  rock  is  granite.  Clear,  transpar- 
ent and  tough  mica  plates  are  used  in  various  ways, 
the  principal  utilization  being  for  stove  and  furnace 
doors.  A  small  amount  of  specially  fine  mica  is  used 
for  compass  plates.  The  inferior  varieties  not  suitable 
for  the  above  uses  are  largely  used  as  an  insulating 
substance  in  electrical  machinery;  while  the  scrap 
trimmings  of  the  better  kinds,  as  well  as  large  quanti- 
ties of  the  inferior  sorts,  are  pulverized  and  used  as  an 
absorbent  for  nitro-glycerine  explosives,  and  also  in 


244        PROSPECTING  AND  VALUING  MINES. 

the  composition  of  lubricating  compounds;  as  well  as 
for  various  ornamental  purposes  in  the  arts. 

Mica  only  in  plates  of  large  size  and  good  color 
has  any  high  commercial  value.  For  such  plates 
the  price  increases  more  rapidly  than  the  size 
of  the  plates,  which  may  be  said  to  range  in  value 
from  25c.  to  $5  per  lb.,  with  occasionally  higher 
prices  for  exceptionally  large  and  good  plates.  The 
industry  in  the  United  States  fluctuates  very  greatly 
both  in  the  quantity  produced  and  its  average  value, 
chiefly  owing  to  the  uncertain  character  of  the 
deposits,  which  may  suddenly  become  worthless. 

From  the  peculiar  conditions  of  the  mica  trade 
it  is  evident  that  good,  large  plates  can  bear  somewhat 
high  rates  of  freight,  and  can  be  worked  in  out  of  the 
way  localities,  but  if  of  only  small  or  moderate  size, 
the  necessity  for  cheap  labor  in  dressing  and  cutting 
the  blocks,  and  freight  charges,  may  render  the 
deposit  valueless,  especially  if  the  cost  of  mining  is 
high,  as  large  quantities  of  material  must  often  be 
moved  to  secure  a  few  pounds  of  plates,  the  conditions 
being  very  much  the  same  as  surround  mining  for 
asbestos. 

The  scales  of  yellow  mica,  found  in  the  streams  of 
granite  and  schistose  mountains,  are  frequently  mis- 
taken for  gold  by  the  uninitiated,  but  can  easily  be 
distinguished  by  their  softness  and  light  weight,  as 
well  as  by  their  loss  of  the  yellow  color  when  ground 
to  powder. 

OZOKERITE. — Like  wax  or  spermaceti  in  appearance 
and  consistency.  G.  0.85 — 0.90.  Colorless  to  white 
when  pure;  often  leek-green,  yellowish,  brownish 
yellow  or  brown;  and  when  brown,  sometimes 
green  by  transmitted  light  through  thin  shavings. 
Greasy  to  the  touch.  Melts  at  133°  to  146°  F.  Burns 
readily  in  thin  shavings  or  at  the  angles  of  specimens, 
when  ignited  with  a  match.  (Dana  in  part.)  Ozoker- 
ite, or  native  paraffin,  is  not  a  common  product  in 


USEFUL  EARTHY  MINERALS,  245 

nature.  It  occurs  in  beds  of  coal  or  associated  with 
bituminous  substances.  In  the  United  States  it  is 
found  in  Utah.  Abroad  it  occurs  at  Slanik,  Moldavia, 
beneath  a  bed  of  bituminous  clay  shale;  in  masses  of 
sometimes  80  to  100  lb.,  at  the  foot  of  the  Car- 
pathians, not  far  from  beds  of  coal  and  salt;  that  of 
Boryslan  in  a  bituminous  clay,  associated  with  calcif- 
erous  beds  in  masses.  It  is  also  reported  from  the 
Carpathian  sandstones  in  Transylvania  and  other  less 
important  localities.  Ozokerite,  mineral  wax  or 
native  paraffin  is  used  in  the  manufacture  of  candles 
and  heavy  lubricants,  very  extensively  as  an  insulator 
for  electrical  wiring,  and  generally  as  a  substitute  for 
most  of  the  uses  of  beeswax. 

PUMICE  STONE  is  an  exceedingly  porous,  spongy- 
looking  lava  in  which  the  air  bubbles  are  so  numerous 
that  it  will  float  on  water,  and  varies  in  color  from 
dirty  white  to  pearly  gray.  It,  aside  from  its  use  as  a 
toilet  article,  is  chiefly  employed  in  polishing  marble. 
The  bulk  of  the  article  is  imported  in  the  lump  for 
use  in  the  Eastern  States  from  Italy,  where  it  is  found 
abundantly  on  Mount  Vesuvius;  while  most  of  that 
used  on  the  Pacific  Coast  is  produced  in  California 
from  deposits  at  Lake  Honda,  a  few  miles  south  of  San 
Francisco.  Other  deposits  of  good  quality  also  occur 
in  California,  near  Mono  Lake,  which  is  the  crater  of 
an  extinct  volcano,  and  at  Little  Owens  Lake  and 
other  localities  in  Inyo  County.  The  annual  con- 
sumption is  not  large  and  the  price  low,  so  that  cheap 
transportation  is  essential. 

QUARTZ. — H.  7.0.  G.  2.6.  Luster  vitreous  or  glassy 
to  nearly  dull.  Colorless  when  pure;  often  various 
shades  of  yellow,  red,  brown,  green,  blue,  purple  and 
black,  Streak  white  of  pure  varieties;  when  impure 
often  similar  in  color,  but  paler.  Transparent  to 
opaque.  Quartz  takes  many  forms,  and  is  one  of 
the  commonest  minerals,  but  is  chiefly  used  commer- 
cially in  the  condition  of  sand>  sandstone  or  quartzite. 


246         PROSPECTING  AND  VALUING  MINES. 

Beds  of  sand  and  sandstone  are  common  everywhere, 
but  they  are  not  all  available  for  the  same  class  of 
work  on  account  of  the  associated  impurities,  and 
their  value  for  any  particular  purpose  can  only  be 
thoroughly  ascertained  by  working  tests. 

The  finest  kinds  of  transparent  quartz,  known  as 
" rock-crystal,"  are  or  rather  were  extensively  used  in 
the  manufacture  of  spectacle  glasses,  but  the  improve- 
ments in  glass  making  have  diminished  this  applica- 
tion. Similar  quartz  is  used  extensively  in  glass  and 
pottery  making,  and  as  a  grinding  and  polishing 
powder.  Ground  quartz  is  also  used  in  the  manufac- 
ture of  sandpaper.  In  addition  to  these  a  peculiar 
variety  of  sandstone  called  "ganister"  is  largely  used 
in  the  lining  of  vessels  used  in  the  manufacture  of 
steel  on  account  of  its  excessively  refractory  character. 
In  England  the  ganister  preferred  for  lining  is  a 
peculiar  silicious  deposit  found  under  a  thin  coal  seam 
near  Sheffield,  of  almost  conchoidal  fracture,  thereby 
differing  from  ordinary  sandstone,  and  containing  a  few 
tenths  per  cent.,  or  sometimes  a  little  more,  of  lime, 
and  the  same  amount  of  alumina,  with  small  quantities 
of  iron  oxide  and  alkalies,  the  rest  being  silica; 
analagous  substances  are  found,  however,  in  other 
localities  in  the  northern  coal  tields.  Beds  of  such 
quartz  in  the  vicinity  of  steel  works  are  valuable. 

For  mortar  making,  river  sand  is  preferable,  as  salt 
from  sea  sands  will  certainly  make  its  appearance  on 
brickwork  where  it  is  used,  spoiling  the  looks  of  the 
building  as  well  as  being  objectionable  on  account  of 
absorbing  moisture;  it  is  also  sharper,  with  less 
rounded  angles,  as  in  rapid  streams  much  of  it  is  car- 
ried down  suspended  in  the  water  and  the  angles 
scarcely  suffer  any  abrasion. 

STRONTIA,  STRONTIANITE,  ETC. — The  metal  strontium 
occurs  as  a  carbonate,  under  the  name  of  strontia- 
nite,  and  as  a  sulphate,  under  the  name  celestite.  When 
crystallized  strontianite  has  a  hardness  of  3.5 — 4,  and 


USEFUL  EARTHY  MINERALS.  347 

a  specific  gravity  of  3.65,  with  a  vitreous  or  resinous 
luster,  and  white  streak.  In  color  it  is  pale  asparagus- 
green  or  apple-green ;  white,  gray,  yellow  and  yellow- 
ish brown.  Transparent  to  translucent.  (Dana.)  It 
occurs  in  the  United  States  in  granular  and  columnar 
masses  in  hydraulic  limestones  at  Schoharie,  N.  Y.  ; 
and  at  Muscalonge  Lake  in  the  same  State,  a 
massive  and  fibrous  variety  of  a  white  or  greenish 
white  color  is  found  associated  with  fluorspar.  In 
Scotland  it  occurs  in  veins  traversing  gneiss,  along 
with  galena  and  bante  (barytes).  (Dana.) 

Celestite  has  a  hardness  of  3 — 3.5  and  sp.  gr.  of 
3.95,  being  somewhat  softer  and  heavier  than  stron- 
tianite.  The  luster  is  vitreous  inclining  to  pearly 
when  crystallized,  and  the  streak  white.  The  color 
white,  often  bluish  (from  which  it  takes  its  name)  and 
sometimes  reddish.  More  or  less  transparent.  (Dana.) 
Celestite  is  usually  associated  with  limestone  or  sand- 
stone, and  occurs  also  in  beds  of  gypsum,  rock  salt 
and  clay.  (Dana.)  In  the  United  States  it  is  reported 
from  the  limestones  about  Lake  Huron ;  from  New 
York  and  Pennsylvania,  and  also  from  Green  orStron- 
tian  Island,  Lake  Erie. 

Nitrate  of  strontia  is  used  to  a  considerable  extent  by 
the  makers  of  fireworks  for  the  production  of  red  fire. 
The  use  of  strontia  has  also  been  proposed  in  the  treat- 
ment of  beet  sugar,  and  in  the  manufacture  of  tuyeres 
for  blast  furnaces.  Sicily  furnishes  the  bulk  of  the 
mineral  at  the  present  time,  but  little  search  for  it 
having  been  made  in  the  United  States  on  account  of 
the  small  demand. 

SULPHUR  cannot  be  mistaken  for  any  other  mineral, 
its  brilliant  yellow  color,  and  characteristic  odor  on 
burning,  separating  it  instantly  from  all  others- 
"Wherever  found  it  appears  to  be  associated  with  vol- 
canic action  and  hot  springs,  having  been  deposited 
by  such  agencies  in  vast  beds  both  in  Europe  and 
America.  In  boring  for  petroleum  near  Lake  Charles, 


248        PROSPECTING  AND  VALUING  MINES. 

Calcasieu  Parish,  Louisiana,  "at  a  depth  of  423  ft.  the 
drill  passed  through  100  ft.  of  pure  sulphur  and  148 
ft.  of  gypsum  mixed  with  sulphur,  the  former  mineral 
being  a  common  associate  of  sulphur  deposits,  by  the 
conversion  of  ordinarj7  limestone  into  the  sulphate 
through  the  action  of  sulphuric  acid.  In  Nevada,  the 
beds  near  Silver  Peak  are  traversed  by  seams  of  alum, 
formed  in  a  similar  way  by  the  decomposition  of 
aluminous  or  clay-forming  rocks.  In  California,  at 
the  Sulphur  Banks  in  Lake  County,  the  deposits  are 
associated  with  cinnabar  or  mercury  and  borax.  In 
Southern  Utah  the  occurrence  is  evidently  in  what  was 
formerly  a  crater  of  a  volcano,  about  three  miles  from 
Fort  Cove  Creek.  The  crater  forms  a  small  basin  sur- 
rounded by  low  hills  with  a  narrow  ravine  opening 
into  the  plain — probably  a  breach  in  the  old  crater 
wails — which  consist  mainly  of  andesite  with  some 
pale  whitish  trachyte  (both  porphyries)  with  obsidian 
splinters  scattered  over  the  surface.  As  far  as  explored 
the  sulphur  beds  extend  over  an  area  of  at  least  1,800 
by  1,000  ft.  across.  The  sulphur  shows  upon  the  sur- 
face over  part  of  the  basin,  but  is  mostly  covered  with 
sand,  or  rather  the  disintegrated  andesite  of  the  sur- 
rounding hills.  A  curved  cut  through  the  western 
end  of  the  deposit  exposes  a  vertical  wall  of  rich  yellow 
sulphur  34  ft.  high,  from  which  in  many  places,  as 
well  as  in  other  prospect-holes,  gases  escape,  together 
with  water  holding  various  salts  in  solution."  "At  the 
Mammoth  claim  in  the  same  neighborhood,  the  slates 
and  limestones  are  impregnated  with  sulphur,  gypsum 
being  also  found  as  a  product  of  altered  limestones; 
while  at  the  Sulphur  King  claim  the  andesifes  are 
similarly  saturated." 

The  depositio'n  of  sulphur  is  constantly  going  on  at 
volcanic  vents  and  many  hot  springs.  "Mount  Purace, 
in  Colombia,  wears  a  cap  of  sulphur  (derived  from  its 
own  crater)  which  accumulates  at  the  rate  of  2  ft.  per 
annum — its  superficial  area  amounting  to  1,435  sq, 


USEFUL  EARTHY  MINERALS.  249 

yards;"  and  the  sulphur  forming  in  the  crater  of  Popo- 
catapetl,  in  Mexico,  is  regularly  worked  by  the  Indians. 
The  salfatara  of  Bahara  Saphinque  on  the  Red  Sea  is 
said  to  yield  600  tons  of  sulphur  annually.  American 
sulphur  comes  into  sharp  competition  with  that  pro- 
duced by  the  Sicilian  deposits  (which  have  been  worked 
to  a  depth  of  over  300  ft.  and  turn  out  annually 
400,000  tons  of  clean  sulphur),  and  can  consequently 
only  be  profitably  exploited  under  the  most  favorable 
conditions  of  labor  and  transportation  aided  by  local 
demand,  which  it  fostered  by  the  high  rates  of  freight 
on  sulphuric  acid  on  account  of  its  dangerous  char- 
acter. Native  sulphur  is  also  met  in  the  market  by 
acid  produced  from  iron  and  copper  pyrites,  which  are 
now  mined  in  enormous  quantities  for  that  purpose, 
as  the  contained  metals  furnish  a  valuable  by-product. 

The  larger  portion  of  the  entire  product  of 
sulphur  is  used  in  the  manufacture  of  sulphuric  acid, 
the  consumption  of  which  in  manufactures  is  extend- 
ing daily.  Outside  of  this  it  is  employed  in  the  pro- 
duction of  vulcanized  rubber  goods;  in  the  manufac- 
ture of  "bluestone, "  or  sulphate  of  copper,  which  is 
largely  used  in  metallurgical  operations;  as  a  preven- 
tative  of  and  cure  for  mildew  on  plants  by  horticul- 
turists, and  many  minor  uses. 

TALC  AND  SOAPSTONE. — H.  1 — 1.5.  G.  2.65.  Luster 
pearly.  Color  apple-green  to  white,  or  silvery  white; 
also  greenish  gray  and  dark  green;  brownish  to 
blackish  green  and  reddish  when  impure.  Streak 
usually  white;  of  dark-colored  varieties,  lighter 
than  the  color.  Easily  cut  with  a  knife.  Thin 
sheets  flexible,  but  not  elastic.  Feels  greasy.  (Dana.) 
The  foregoing  description  is  of  the  purer  and  softer 
varieties,  from  which  the  harder  kinds  are  separated  as 
"soapstone, "  to  the  best  kinds  of  which  the  term 
"French  chalk"  is  applied.  The  mineral  is  soft  enough 
to  leave  a  whitish  mark  on  cloth,  and  is  used  by  tailors 
in  drawing  their  patterns.  The  various  forms  of  talc  are 


250         PROSPECTING  AND  VALUING  MINES. 

of  very  common  occurrence;  and  steatite  or  soapstone 
forms  extensive  beds  in  some  regions,  being  often 
associated  with  serpentines,  chloritic  or  talcose  schists, 
in  which  latter  rock  thin  flakes  of  talc  take  the  place 
of  mica,  and  impart  to  it  a  certain  greasy  feel,  which 
is  characteristic  of  the  entire  series  of  minerals  asso- 
ciated under  the  name,  which  is  often  applied  by  miners 
and  prospectors  to  any  soft  white  earthy  substance  in 
the  gouge  of  veins,  whether  greasy  or  not.  Talc  is 
used  extensively  in  soap  making,  and  in  dressing  fine 
sheep-skins,  leather,  gloves,  etc.  The  finer,  soft,  foli- 
ated variety  is  used  in  the  manufacture  of  paper,  and 
small  quantities  enter  into  the  composition  of  some 
lubricating  compounds.  "Soapstone,"  OD  account  of 
its  refractory  nature  in  the  presence  of  intense  heat, 
and  the  facility  with  which  it  can  be  sawn  into  bricks, 
slabs  or  any  desirable  shape,  is  extensively  used  as 
a  lining  for  stoves,  furnaces,  etc.  It  can  be  easily 
turned  in  a  lathe,  and  the  writer  has  seen  on  the 
Mexican  border  a  very  ancient  tuyere  for  a  black- 
smith's forge  made  out  of  such  material.  It  was 
found  in  grading  for  a  ditch,  and  from  the  size  of  the 
trees  growing  over  the  spot  must  have  been  buried  for 
at  least  100  years,  and  may  possibly  be  a  relic  of  the 
early  missionary  days  of  California. 

II.    SOLUBLE    MINERALS. 

With  the  exception  of  common  salt,  which  is  of  gen- 
eral distribution,  and  Stassfnrt  salt  and  its  associ- 
ates, the  balance  of  the  useful  minerals  of  t'his  group 
all  occur  in  arid  regions,  where  the  climatic  con- 
ditions favor  the  evaporation  of  the  water  which  dis- 
solves the  various  salts  and  holds  them  in  suspension. 
Many  of  them  are  found  in  foreign  countries  where 
the  price  of  labor  is  extraordinarily  low,  and  from 
which  ocean  carriage  is  remarkably  cheap,  so  that  the 
products  of  the  United  States  being  found  far  inland, 
in  thinly  populated  regions  and  often  in  consequence 


USEFUL  EARTHY  MINERALS.  251 

far  from  convenient  lines  of  transportation,  can  with 
difficulty  compete  with  the  imported  articles.  The 
efflorescences  or  crusts  of  borate  of  soda,  carbonate  of 
soda  and  salt  greatly  resemble  each  other,  but  can  be 
separated  by  the  tests  given  in  the  description  of  these 
minerals,  the  presence  of  carbonate  of  soda  being  indi- 
cated by  effervescence  if  citric  acid  be  added  to  a  solu- 
tion of  the  incrustation,,  The  compact  massive 
deposits  found  underlying  these  incrustations  may 
also  be  tested  in  the  same  manner,  and  while  under 
existing  conditions  of  trade  and  transportation  they 
may  not  be  available  for  other  than  local  consumption, 
they  may  possibly  supply  a  mineral  which  will  render 
others  available,  just  as  cheap  soda  is  necessary  to 
make  quartz  sand  valuable  for  the  production  of  glass. 

BORAX. — H.  2 — 2.5.  G.  1.7.  Luster  vitreous  to 
resinous,  sometimes  earthy.  Color  white,  sometimes 
grayish,  bluish  or  greenish.  Streak  white.  Trans- 
lucent to  opaque.  Bather  brittle.  Taste  sweetish- 
alkaline.  Imparts  a  clear  green  color  to  the  flame. 
Boiling  water  dissolves  double  its  weight  of  borax. 
(Dana.) 

Borate  of  Lime,  Ulexite  or  Hayesine. — H.  1.0. 
G.  1.65.  Color  white.  Tasteless.  Loose  in  texture, 
fibrous  and  silky,  usually  in  rounded  masses. 

Crystallized  borax  (or  borate  of  soda)  is  found 
in  the  mud  of  certain  lakes  both  in  California 
and  Asia,  but  the  great  bulk  is  produced  from  the 
borate  marshes  of  Nevada  and  California,  of  which  the 
general  character  is  well  described  in  the  Geological 
Survey  reports  of  1883.  "The  borate  fields  are  situ- 
ated in  the  extensive  salines  known  as  Teel's  marsh, 
Bhodes's  marsh,  the  Columbus  marsh  and  Fish  Lake 
Valley,  all  in  the  southeasterly  part  of  Esmeralda 
County.  These  salines  consist  of  oval-shaped  alkali 
flats  occupying  the  centers  of  immense  basins,  and 
cover  from  10,000  to  20,000  acres  each.  These  basins 
are  surrounded  for  the  most  part  by  a  broad  margin 


262         PROSPECTING  AND  VALUING  MINES, 

of  sage  plains  which  rise  gradually  to  the  base  of  the 
hills  and  mountains  which  inclose  them  on  every 
hand.  They  have  no  outlets,  and,  receiving  the 
drainage  of  the  country  around,  retain  everything 
brought  into  them,  including  the  borates  and  salts  of 
various  kinds.  From  midsummer  till  late  in  the 
spring,  when  the  snow  commences  to  melt  on  the 
mountains,  these  saliniferous  lands  are,  as  a  general 
thing,  apt  to  be  dry,  only  shallow  lakes  occupying 
sometimes  their  points  of  greatest  depression.  At 
other  seasons  of  the  year  portions  of  them  are  covered 
with  water  to  the  depth  of  a  foot  or  two.  Heavy 
rains,  though  these  seldom  occur  in  these  regions,  con- 
vert these  alkali  flats  into  beds  of  tenacious  mud,  even 
a  slight  shower  rendering  their  passage  by  teams  dif- 
ficult for  the  time  being.  Water  can  be  obtained  on 
these  salines  almost  anywhere  by  digging  from  2  or  3 
to  10  or  15  ft.  below  the  surface.  It  is  general!}' 
brackish,  however,  often  so  much  so  as  to  be  scarcel^ 
fit  for  drinking.  By  digging  to  much  greater  depths 
good  water  is  obtained  a  short  distance  back  from  the 
edge  of  the  marsh.  Over  large  sections  of  these  flats 
exist  deposits  of  common  salt,  carbonate  of  soda,  and 
borax.  This  latter  mineral  does  not,  however,  occur 
here,  as  at  Clear  Lake  in  California,  in  the  shape  of 
compact,  semiopaque  crystals  imbedded  in  mud,  but 
generally  in  the  form  of  borate  of  lime  or  soda.  The 
former  is  found  at  many  spots  imbedded  in  these 
marshes  from  1  to  4  ft.  below  the  surface.*  It  crystal- 
lizes in  long  silky  fibers  which  gather  into  balls  from 
an  eighth  of  an  inch  to  2  or  3  in.  in  diameter.  These 
globular  masses  have  the  luster  of  white  satin,  and 
when  dug  up  readily  separate  from  the  inclosing 
earth.  The  borate  of  soda  mixed  with  sand  and  other 
impurities  accumulates  on  the  surface  in  the  shape  of 
a  dark-colored  incrustation  an  inch  or  two  thick. 
This  crust  when  dry,  being  hard  and  brittle,  can  be 
easily  detached  from  the  moister  ground  beneath  and 
broken  into  fragments/' 


USEFUL  EARTHY  MINERALS.  253 

While  Nevada  and  California  are  the  only  produc- 
ing States  in  North  America,  there  are  extensive 
deposits  in  Europe,  India,  Peru  and  Asiatic  Turkey, 
and  competition  has  reduced  the  price  from  the  old 
standard  of  25  or  30  c.  per  Ib.  to  a  very  low  figure, 
the  reduction  having,  however,  opened  up  new  avenues 
of  use. 

The  leading  uses  of  borax  are  in  welding  (for  which 
the  greater  part  is  consumed  in  iron  and  steel  manu- 
facture); in  refining  metals  as  a  crucible  flux;  in 
enamelling;  by  packers,  in  preserving  meat;  and  as  a 
detergent  for  household  purposes. 

CARBONATE  OF  SODA  OR  TRONA. — H.  2.5 — 3.0,  G. 
2.10.  Luster  vitreous,  glistening.  Color  gray  or 
yellowish  white.  Translucent.  Taste  alkaline.  Not 
altered  by  exposure  to  a  dry  atmosphere.  (Dana.) 
Soluble  in  water  and  effervesces  with  acids.  Trona 
is  another  of  the  minerals  occurring  as  the  result  of 
the  evaporation  of  water  in  dry  inland  basins  without 
drainage  outlets.  The  following  description  of  one 
such  deposit  will  convey  a  good  idea  of  them  all : 

"This  mineral  abounds  throughout  most  parts  of 
the  Great  Basin,  the  extensive  alkali  flats  which  form 
a  feature  of  that  region  constituting  the  principal  sites 
of  these  deposits,  which  occur  usually  in  the  form  of 
an  efflorescence  an  inch  or  two  thick  on  the  surface, 
but  sometimes  in  strata  a  foot  or  more  thick  imbedded 
in  the  earth,  and  separated  from  each  other  by  thin 
seams  of  clay.  When  found  in  the  form  of  a  thin 
incrustation  on  the  surface  it  is  never  pure,  being 
always  admixed  with  salt,  borax,  lime,  magnesia  and 
other  minerals.  The  heavier  deposits  are  compara- 
tively free  from  foreign  matter,  carrying  generally 
about  90%  carbonate  of  soda.  One  of  the  most  re- 
markable repositories  of  this  mineral  known  consists 
of  a  circular  basin,  the  bed  of  a  former  lake,  situated 
on  the  southerly  margin  of  the  Forty-mile  desert, 
Churchill  County,  Nev.  This  basin,  which  covers 


254         PROSPECTING  AND  VALUING  MINES. 

an  area  of  10  or  12  acres,  is  depressed  60  ft.  below  the 
common  level  of  the  country  adjacent.  Its  bottom, 
usually  dry,  though  in  wet  seasons  oovered  with  a  few 
inches  of  water,  is  composed  of  a  compact  mass  of  the 
carbonate  of  soda  so  hard  that  it  ,has  to  be  broken  out 
with  crowbars,  and  so  pure  that  it  can  for  many  pur- 
poses be  used  to  advantage  in  its  natural  state.  This 
substance  occurs  here  in  layers  about  1  foot  thick, 
separated  from  each  other  by  thin  seams  of  clay. 
Large  quantities  of  the  crude  material  are  extracted 
every  year. "  This  deposit  has  been  worked  over  an 
area  of  several  acres  to  a  depth  of  10  or  12  ft.  without 
showing  any  signs  of  exhaustion.  A  portion  of  the 
product  from  the  above  locality  is  used  in  the  working 
of  the  neighboring  silver  ores,  but  the  greater  portion 
is  refined  and  sold  for  other  purposes,  soda  being  very 
extensively  employed  both  in  the  arts  and  manufac- 
tures. 

NITRATE  OF  POTASH,  NITER  OR  SALTPETER. — H.  2,0. 
G,  .1.9.  Luster  vitreous.  Streak  and  color  white. 
Subtransparent.  Brittle.  Taste  saline  and  cooling. 
Deflagrates  vividly  on  burning  coals,  and  detonates 
when  mixed  with  combustible  substances.  (Dana.) 
Dissolves  easily  in  water  and  is  not  altered  by  expo- 
sure. Colors  the  flame  violet  when  burned.  It  occurs 
as  an  efflorescence  on  the  surface  or  in  the  surface 
stratum  of  the  soil  in  many  parts  of  the  world,  but 
especially  to  a  great  extent  in  the  valley  of  the  Ganges 
and  other  parts  of  India,  as  well  as  in  Spain,  Egypt 
and  Persia.  It  is  also  obtained  in  a  semi-artificial 
manner  in  nitaries  or  saltpeter  plantations.  These 
consist  of  heaps  of  decomposing  animal  matter,  mixed 
with  lime,  ashes,  road  scrapings  and  other  rubbish, 
covered  over  from  rain,  and  from  time  to  time  damped 
with  the  runnings  from  stables  and  other  urine.  Such 
heaps  develop  within  them  small  proportions  of  the 
salt,  and  other  nitrates,  and  are  in  effect  artificial 
imitations  of  the  saltpeter-bearing  soil  of  India. 


USEFUL  EARTHY  MINERALS.  255 

Niter  requires  for  its  formation  dry  air  and  long 
periods  without  rain,  and  is  produced  most  abun- 
dantly during  hot  weather  succeeding  rain.  The 
potash  comes  mainly  from  the  debris  of  feldspathic 
rocks  in  the  soil.  (See  chapter  on  rocks  for  the  per- 
centages of  potash  in  various  kinds  of  rocks.)  It  also 
forms  abundantly  on  the  walls  of  caverns  and  in  the 
loose  earth  floors  of  the  same,  which  abound  in  the 
limestones  of  the  Mississippi  Valley  in  Kentucky  and 
Tennessee.  It  is  now  prepared  artificially  from  Chili- 
saltpeter  and  the  German  chloride  of  potash,  by 
mutual  decomposition,  producing  chloride  of  sodium 
or  common  salt  and  nitrate  of  potash,  or  saltpeter/and 
this  product  has  largely  supplanted  the  native  article, 
being  a  much  superior  material. 

India  furnishes  the  bulk  of  the  imported  niter. 

NITRATE  OF  SODA  OR  CHILP-SALTPETER. — JL  1.5 — 
2.0.  G.  2.0 — 2.3.  Luster  vitreous.  Color  white; 
also  reddish  brown,  gray  and  lemon-yellow.  Trans- 
parent. Bather  sectile  instead  of  brittle.  Taste  cool- 
ing. Deflagrates  with  less  violence  than  niter,  and 
colors  the  flame  yellow ;  also  absorbs  water  on  ex- 
posure to  moisture  and  deliquesces.  (Dana.) 

Chili  saltpeter  occurs  on  exceedingly  dry  and  arid 
plains  in  North  and  South  America  chiefly.  In  South 
America  in  the  district  of  Tarapaca,  Northern  Chili, 
the  dry  pampas  for  40  leagues,  at  a  height  of  8,300  ft. 
above  the  sea,  is  covered  with  beds  of  this  salt  several 
feet  in  thickness,  along  with  gypsum,  common  salt  and 
glauber  salt,  with  remains  of  recent  shells  indicating 
the  former  presence  of  the  sea.  The  arid  plains  of  the 
Great  American  basin  present  almost  identical  condi- 
tions as  regards  altitude,  climate  aud  rainfall  (on  the 
Nevada  deserts  only  about  4  in.  annually),  and  as 
might  have  been  expected,  this  mineral  is  found  on 
the  40-mile  desert  near  Lovelock's  Station,  crystallized 
in  the  crevices  of  rocks  and  imbedded  in  the  earth 
from  2  to  30  in.  below  the  surface.  Its  occurrence  is 


256         PROSPECTING  AND  VALUING  MINES. 

also  reported  in  a  similar  country  near  Calico,  San 
Bernardino  County,  Cal. ;  and  in  the  southern  part  of 
New  Mexico,  near  tbe  Chihuahua  line,  the  mineral  is 
said  to  be  deposited  by  springs  in  considerable  quan- 
tity. 

Nitrate  of  soda  is  used  extensivebr  in  the  pro- 
duction of  nitric  acid  and  saltpeter  or  nitrate  of 
potash,  the  latter  product  entering  into  the  composi- 
tion of  gunpowder. 

SALT  is  sufficiently  well  known  to  be  distinguished 
from  other  similar  minerals,  when  in  comparatively 
pure  condition,  by  its  taste  alone.  Rock  salt  occurs  as 
immense  beds  formed  by  the  evaporation  of  sea  water, 
associated  with  deposits  of  gypsum  and  other  marine 
products.  Percolating  waters  dissolve  these  accumu- 
lations and  supply  the  brines  for  the  salt  wells  of 
Michigan,  New  York  and  other  Eastern  States,  which 
vary  in  depth  from  a  few  up  to  1,000  ft.,  the  average 
depth  in  Michigan  being  882  ft. ;  in  New  York,  322; 
Ohio,  932;  Pennsylvania,  883;  and  Virginia,  1,042  ft. 
The  shallowest  wells  are  in  Utah,  Texas  and  Kansas. 
Some  brines  are  obtained  not  from  beds  of  pure  rock 
salt,  but  from  strata  of  salt-bearing  rocks  such  as 
sandstone,  shale,  etc.  The  brines  from  these  wells 
are  evaporated  by  artificial  heat.  In  California,  solar 
heat  is  extensively  used  in  the  neighborhood  of  San 
Francisco  in  the  evaporation  of  sea  water;  while  in 
Nevada  salt  is  abundant  in  all  the  interior  basins 
either  as  beds  of  rock  salt,  as  incrustations  on  the  sur- 
face, which  are  renewed  as  often  as  they  are  removed, 
and  that  so  rapidly  as  to  afford  several  crops  annually, 
or  as  massive  deposits,  covered  with  slight  deposits  of 
sand  or  clay. 

SULPHATE  OF  SODA.— H.  2.0—3.0.  G.  2.6.  Luster 
vitreous.  Color  white  to  brown.  Translucent. 
Wholly  soluble  in  water.  The  occurrence  is  very 
similar  to  that  of  carbonate  of  soda  just  described,  the 
material  being  found  extensively  in  lakes  and  beds  in 


USEFUL  EARTHY  MINERALS.  257 

the  States  of  Wyoming  and  Colorado,  and  in  smaller 
quantities  in  New  Mexico.  Well  known  localities  are 
the  lake  near  Independence  Rock  and  the  lake  seven 
miles  from  St.  Mary's  Station,  both  in  the  Sweetwater 
valley;  and  Burclsall's  Lake  near  Morrison  in  Colo- 
rado. While  outwardly  appearing  much  the  same, 
analysis  develops  the  occurrence  in  the  deposits  of  car- 
bonate of  soda,  and  common  salt,  in  varying  propor- 
tions, as  well  as  various  impurities  such  an  silica,  lime 
and  magnesia.  Available  in  the  manufacture  of  soda, 
glass  and  gunpowder. 

III.    LIQUID. 

PETROLEUM. — Crude  petroleum  varies  considerably 
in  composition  and  density,  the  latter  varying  from 
0.60  to  0.80,  forming  the  so-called  light  and  heavy 
oils.  The  light  oils  give  proportionately  more  illumi- 
nating oil  (kerosene);  the  heavj7,  more  lubricating  oil 
and  residue.  It  is  a  hydrocarbon,  standing  inter- 
mediate in  the  series  ranging  between  the  asphaltum 
group  of  minerals  at  one  end  to  the  lightest  naphthas 
at  the  other.  Its  exact  origin  is  in  dispute,  but  is 
probably  the  decay  of  animal  and  vegetable  substances 
under  peculiar  conditions.  It  is  usually  dark  green- 
ish brown  in  color,  and  is  easily  recognizable  by  its 
peculiar  fetid  odor.  Its  inflammability  varies  and  is  not 
always  a  reliable  test,  as  some  specimens  (of  the  heavy 
or  impure  varieties)  do  not  ignite  very  readily.  In  the 
United  States  the  light  oils  are  found  mainly  in  the 
eastern  fields;  from  Ohio  westward  the  oils  are  usually 
of  the  heavy  variety.  It  occurs  in  porous  sedimentary 
rocks  of  all  kinds,  as  in  sandstones,  shales  and  some 
limestones;  and  in  point  of  geologic  age  all  the  way 
from  the  Silurian  to  the  most  recent.  At  the  surface 
it  appears  as  springs,  pools  and  as  a  scum  floating  upon 
the  water.  The  surface  prospecting  consists  merely  in 
following  streams  showing  such  oil  films  up  to  the 
source  of  the  petroleum  spring  or  oil-bearing  rock 


258         P  INSPECTING  AND  VALUING  MINES. 

outcrop.  Borings  for  oil  in  depth  are  generally  di- 
rected in  accordance  with  the  results  found  in  existing 
wells  of  the  neighborhood ;  though  sometimes  bore 
holes  are  put  down  in  localities  far  from  any  previously 
sunk  wells,  where  geologic  reasoning  shows  the  proba- 
bility of  the  presence  underground  of  oil-bearing 
strata  which  have  been  proved  elsewhere.  Boring  for 
oil  is  a  special  trade,  based  partly  upon  theoretical 
and  geological  considerations  but  more  especially 
upon  local  experience. 

iv. — GASEOUS. 

NATUKAL  GAS  also  is  a  hydrocarbon,  something  like 
the  "marsh  gas"  which  sometimes  rises  from  swamps, 
and  also  related  to  the  "fire  damp"  of  coal  mines.  It 
is  colorless  and  odorless,  and  is  lighter  than  ordinary 
illuminating  gas.  Its  discovery  in  a  new  locality 
usually  results  from  accidental  ignition ;  in  regions 
where  it  is  already  known  to  exist  borings  for  it  are 
put  down  in  accordance  with  the  indications  given  by 
earlier  gas  wells,  or  to  strike  a  stratum  which  has  been 
gas-bearing  elsewhere. 


CHAPTEE  XV. 
COAL, 

THE  literature  of  coal  is  so  extensive  and  complete, 
and  coal  mining  is  so  essentially  a  business  in  itself, 
that  in  a  work  intended  chiefly  for  the  use  of  the  pros- 
pector for  ores  a  long  account  of  coal  would  be  useless 
and  out  of  place.  This  chapter  will  therefore  be  de- 
voted to  the  presentation  of  only  those  points  which 
may  be  serviceable  to  the  prospector  who  may  come 
across  outcrops  of  coal  while  searching  for  other 
minerals,  so  that  he  may  be  able  to  estimate  their 
value  as  aids  in  the  reduction  of  metallic  ores. 

ORIGIN. — The  general  origin  of  all  coal  beds  is  the 
same.  Masses  of  vegetation  were  laid  down  in  water 
in  a  horizontal  position,  or  nearly  so;  and  then,  ow- 
ing to  geological  changes,  covered  up  and  buried  by 
the  rocks  we  now  find  above  them,  undergoing  in 
process  of  time,  through  pressure  and  heat,  certain 
chemical  changes,  which,  according  to  the  period  of 
time  which  has  elapsed  since  their  formation,  have 
been  more  or  less  extensive;  so  that  to-day  we  recog- 
nize several  varieties,  distinguished  chiefly  by  their 
percentages  of  carbon  and  volatile  matter,  imparting 
to  them  different  qualities.  The  character  of  the 
rocks  on  which  beds  of  salt,  gypsum,  iron  ore,  etc.,  are 
deposited  is  purely  accidental  and  unimportant,  but 
in  the  case  of  coal  the  wide  marshes  demanded  a  reten- 


260         PROSPECTING-  AND  VALUING  MINES. 

tive  bottom  to  prevent  drainage,  and  we  consequently 
usually  find  a  floor  of  clay,  often  fire  clay,  without 
which  we  cannot  imagine  the  formation  of  such 
enormous  accumulations  of  vegetable  matter,  which 
before  compression  reduced  them  to  their  present  con- 
dition must  have  had  a  thickness  from  ten  to  twenty 
times  that  which  they  now  exhibit.  The  edges  of  coal 
deposits  are  likely  to  be  largely  contaminated  with 
sand  and  clay  or  other  waste  matter;  and  it  is  easy  to 
see,  if  the  deposit  be  of  small  area,  how  this  worthless 
margin  may  form  a  much  larger  proportion  of  the 
whole  bed  than  in  those  of  greater  extent,  as  in  the 
case  of  coal  we  must  picture  to  ourselves  immense 
level  marshy  tracts,  covered  with  a  dense,  luxuriant 
vegetation  which  would  certainly  intercept  any  wind- 
blown debris  before  it  had  traveled  far  from  the 
margins  of  the  swamp,  or  would  entangle  in  its  roots 
the  sediment  brought  down  by  streams,  the  velocity  of 
whose  currents  would  be  promptly  checked,  and  con- 
sequently they  would  drop  their  burden. 

COMPOSITION. — As  a  general  proposition  the  percent- 
age of  carbon  is  greatest  in  those  coals  which  are 
the  oldest  geologically.  Coal  contains  a  certain 
amount  of  "fixed"  carbon,  or  that  which  remains  after 
coking,  and  also  a  certain  amount  of  carbon  in  com- 
bination with  hydrogen,  oxygen  and  nitrogen,  forming 
the  volatile  portion ;  the  remainder  is  earthy  matter 
(forming  ash)  and  moisture.  The  following  table, 
from  Andre's  "Practical  Treatise  on  Coal  MiniDg" 
(which  may  be  consulted  for  all  details),  is  very  in- 
structive, showing  that  with  age,  in  the  sense  of  geo- 
logic time,  coal  loses  the  gaseous  elements,  particularly 
oxygen  and  nitrogen,  consequently  containing  a  larger 
percentage  of  carbon,  and  steadily  increasing  in 
specific  gravity.  An  important  exception  is  found  in 
the  case  of  comparatively  recent  coals  which  have 
been  heated  and  altered  by  the  proximity  (not  actual 
contact)  of  igneous  dikes  or  overflows,  producing  the 


COAL. 


261 


same  effect  as  age.     Colorado  and 
are  examples.     The    percentages 
spective  of  ash  and  moisture. 


are 


other  anthracites 
calculated  irre- 


COMPARISON  OF  CARBONACEOUS  SUBSTANCES. 


Substance. 

Specific 
Gravity. 

Carbon. 

Hydro- 
gen. 

Oxygen 
and 
Nitrogen. 

Wood  —  mean  of  12  kinds  

Per.  Cent 
0.91 
0.99 
1.25 

1.27 

1.30 
1.37 
1.50 

Per  Cent. 
49.00 
59.30 
72.37 

80.07 

86.17 
91.00 
92.50 

Per  Cen 
6.25 
6.52 
5.18 
5.53 

5.21 
4.75 
3.75 

Per  Cent. 
44.75 
34.18 
23.45 
13.50 

8.62 
5.25 
3.75 

Peat    mean  of  12  samples 

Lignite  —  mean  of  12  samples       .... 

Cannel  coal 

Bituminous  coal—  mean  of  3  divi- 
sions   

Semi-bituminous  coal  —  mean 

Anthracite  coal  —  mean     

CLASSIFICATION. — 'The  classification  and  names  of  coal 
are  based  on  the  foregoing  percentages.  A  portion  of 
the  gases  are  combined  to  form  water,  while  the  re- 
mainder of  the  gases  are  combined  with  a  portion  of 
the  carbon  in  the  form  of  volatile  matter,  leaving  a 
balance  of  carbon,  which  is  known  as  the  " fixed"  car- 
bon, and  is  that  portion  which  is  left  as  coke  when 
the  volatile  matter  has  been  extracted  by  distillation. 
The  varying  proportions  of  these  materials  render  the 
different  kinds  of  coal  suitable  for  different  purposes. 
Water  in  all  cases  is  a  detriment  to  the  coal,  as  it  must 
be  driven  off  in  th«  form  of  steam  at  the  expense  of  a 
portion  of  the  carbon,  which  is  thus  lost  for  heating 
purposes. 

The  following  classification  of  coals  is  taken  from 
Andre,  and  is  based  on  the  amount  of  coke  produced 
by  distillation.  The  "coke"  in  this  case  does  not 
mean  commercial  coke,  but  the  residue  left  in  labora- 
tory tests.  Neither  anthracite  at  one  extreme  nor 
lignite  at  the  other  make  true  coke. 


PROSPECTING  AND   VALUING  MINES. 

CLASSIFICATION  OF  COALS. 


Name  of  Coal. 

Coke, 
Per  Cent. 

Volatile 
Matter, 
Per  Cent. 

Character  of  Coke. 

93-88 

8-12 

Brittle  and  powdery. 

Semi-bituminous            

88-82 

12-18 

Brittle  and  powdery 

Bituminous  — 
1    Clear-burning     

82-74 

18  26 

Good. 

74-68 

26-32 

Good. 

3    Smoky  or  fuliginous  ... 

68-60 

32-40 

Porous,  friable. 

60-50 

40-50 

Soft,  powdery. 

Lignite  or  brown  coal          

50 

50 

DISTINGUISHING  CHARACTERS  OF  COALS. — Anthracite — • 
— Its  structure  is  perfectly  homogeneous,  its  density 
greater  than  that  of  other  kinds  of  coal,  and  it  has  a 
more  completely  mineralized  appearance.  Its  color  is 
a  jet  black,  with  a  somewhat  vitreous  luster,  often  ex- 
hibiting a  powerful  play  of  colors.  It  does  not 
(easily)  soil  the  fingers  when  handled,  being  very 
hard  and  firm.  In  the  harder  examples,  the  fracture 
is  distinctly  conchoidal,  but  when  of  a  more  tender 
character  it  frequently  breaks  into  small  cubical 
lumps.  Anthracite  burns  with  a  feeble  flame,  blue 
when  the  supply  of  oxygen  is  insufficient,  and  often 
decrepitates  much  in  burning.  It  ignites  with  diffi- 
culty, and  is  slowly  consumed,  but  when  in  a  state  of 
perfect  combustion  it  evolves  intense  heat.  The 
quality  of  hardness  possessed  by  anthracite  enables  it 
to  be  transported  from  place  to  place  without  injury, 
while  that  of  evolving  great  heat  without  smoke 
renclers  it  peculiarly  suitable  for  many  purposes,  as  in 
the  generation  of  steam,  and  employment  in  distil- 
leries, breweries,  or  in  lime  or  brick  kilns.  In 
America  it  is  largely  used  for  domestic  purposes;  also 
for  steam-making  on  naval  vessels  at  times,  and  in 
cities  where  "anti-smoke"  ordinances  prohibit  the  use 
of  bituminous. 

Semi- anthracite  is  a  term  sometimes  used  to  indi- 
cate a  grade  between  strictly  anthracite  and  semi- 
bituminous, 


COAL.  263 

Semi-bituminous  Coal  occurs  Dext  above  the  anthra- 
cites in  geological  order.  Occupying  a  higher  posi- 
tion, it  has  been  less  exposed  to  the  action  of  heat  and 
other  metamorphic  agencies,  and  has  consequently 
retained  a  larger  proportion  of  its  volatile  matter. 
Between  the  anthracitous  and  the  semi-bituminous 
classes,  however,  the  line  of  division  is  purely  arbi- 
trary, since  from  anthracite  to  cannel  there  is  every 
grade  of  composition.  Its  color  is  usually  a  dull 
black  and  its  fracture  subconchoidal.  It  frequently 
exhibits  a  peculiar  fibrous  structure,  passing  into  a 
remarkable  toothed  arrangement  of  the  particles, 
called  " cone-in-cone"  or  crystallized  coal.  It  burns 
with  a  slightly  more  abundant  flame  than  coals  of  the 
anthracitous  class,  and  evolves  more  smoke,  but  not 
in  dense  volumes.  It  possesses  the  dry  character  of 
the  latter  class,  and  from  its  freedom  from  a  liability 
to  cake  together,  it  is  sometimes  called  "free-burn- 
ing/' and  " steam  coal." 

Bituminous  Coal  (Clear-burning  1). — "The  varie- 
ties of  the  clear-burning  division  are  the  poorest  in 
volatile  matter.  They  are  similar  in  texture  to  those 
of  the  preceding  class,  but  generally  of  a  duller  luster. 
They  are  very  tender,  and  break  with  an  even  or  an 
irregular  fracture,  and  in  consequence  of  the  very  per- 
fect development  of  the  cleat*  have  always  a  tendency 
to  break  up  into  small  cubical  lumps.  These  coals 
kindle  with  difficulty,  and  burn  away  slowly  with  a 
short,  clear,  bluish  flame,  and  very  little  smoke. 
When  reduced  to  a  powder  and  heated  in  a  close 
vessel  they  fuse  and  agglomerate  into  a  dense  and 
strongly  coherent  coke,  a  property  which  renders 
them  extremely-  valuable  for  manufacturing  purposes. 
Both  in  quality  and  quantity  the  coke  obtained  from 
the  clear-burning  coals  is  superior  to  that  obtained 
from  any  of  the  more  bituminous  varieties." 

*  Cleat  s  the  system  of  parallel  joints  at  right  angles  to  the  bedding  of 
the  coal. 


264         PROSPECTING  AND   VALUING  MINES. 

Flaming  Coal  (Bituminous  2). — "The  coals  of 
tbis  class  are  richer  in  volatile  matters  than  the  fore- 
going, a  circumstance  to  which  they  owe  their  char- 
acteristic flaming  quality.  Their  structure  is  dis- 
tinctly laminated,  and  their  color  black  and  glossy. 
When  reduced  to  powder,  however,  their  color  is  a 
dark  brown.  They  kindle  without  difficulty,  and 
burn  away  somewhat  rapidly  with  a  long  white  flame. 
Coals  of  this  class  become  partially  fused  when 
strongly  heated,  and  while  in  a  fused  state  swell  into 
a  spongy  mass,  giving  off  bubbles  of  gas,  which  burns 
with  a  bright  flame.  This  property  of  agglutinating 
in  the  fire  allows  the  small  coal  to  be  burned  which 
would  otherwise  be  useless,  or  to  be  converted  into 
coke,  of  which  it  produces  an  excellent  quality.  To 
this  property,  also,  these  coals  owe  the  name  of  'cak- 
ing* coal,  which  has  been  applied  to  it  in  common 
with  some  other  varieties  of  the  same  class/' 

Fuliginous  Coal  (Bituminous  3)  " contain  a  very 
large  proportion  of  volatile  matter.  Hence  they 
kindle  readily,  and  burn  away  rapidly  with  a  long 
yellow  smoky  flame.  They  are  somewhat  hard  and 
strong,  and  their  fracture  is  rather  shaly.  Coals  of 
this  character  fuse  in  the  fire  like  the  flaming  varieties 
but  they  do  not  agglomerate  or  cake  into  so  compact 
a  mass.  The  gas  obtained  from  them  is  abundant  and 
of  a  high  illuminating  power,  but  the  coke  obtained 
from  this  division  is  friable  and  porous,  and  unfit  for 
many  purposes. " 

Gas  Coal  (Bituminous  4). — "All  of  the  foregoing 
coals  occur  in  the  so-called  Carboniferous  period,  but 
some  of  the  present  section  are  found  in  beds  of  later 
geological  times.  They  are  distinguished  by  the  very 
large  proportion  of  volatile  matter  which  they  con- 
tain, and  to  this  circumstance  it  is  due  that  they  do 
not  cake  when  heated.  Experience  has  shown  that 
coal  becomes  caking  when  the  proportion  of  carbon 
reaches  80%,  and  that  of  the  hydrogen  descends  below 


COAL.  265 

on  the  other  hand,  when  the  proportion  of 
hydrogen  becomes  very  small  and  that  of  the  carbon 
large,  as  in  the  anthracites,  the  same  non-caking  qual- 
ities result.  The  gaseous  coals  are  of  a  brownish 
black  color  and  of  a  dull  luster.  When  reduced  to 
powder  they  are  quite  brown.  They  are  generally 
hard,  compact  and  strong;  their  fracture  is  even  to 
conchoidal.  Coals  of  this  class  kindle  even  more 
readily  than  the  fuliginous  varieties,  and  they  burn 
away  rapidly  with  a  long  flame.  The  coke  obtained 
from  coals  of  this  class  is  of  a  soft  and  pulverulent  or 
powdery  character  and  useless  for  commercial  pur- 
poses." 

Cannel  Goal  "naturally  falls  under  the  head  of  a 
gaseous  coal,  though  differing  much  in  appearance. 
It  is  a  very  hard  compact  coal,  of  a  black  or  brownish 
black  color,  sometimes  glossy,  but  more  frequently 
dull  in  luster.  It  does  not  soil  the  fingers  when 
handled,  and  it  is  capable  of  taking  a  high  polish.  It 
breaks  with  a  flat  conchoidal  fracture,  and  is  distin- 
guished from  ordinary  coals  by  the  absence  of  a 
laminated  structure.  This  is  a  mark  of  its  highest 
perfection,  for  when  it  comes  earthy  and  impure  the 
laminated  structure  is  developed.  It  kindles  very 
readily,  and  burns  away  in  the  hand  with  a  very 
abundant  white  flame.  It  is  now  employed  almost 
exclusively  (except  for  grate  fires)  for  gas  making,  for 
which  purpose  it  commands  a  high  price.  Seams  of 
caunel  occur  in  certain  districts  with  ordinary  coal, 
and  often  form  the  upper  portion  of  a  seam  of  bitumi- 
nous coal,  and  occasionally  of  a  bed  of  black-band 
ironstone."  The  splint  coal  of  West  Virginia  aad  other 
States  somewhat  resembles  can nel  in  appearance  and 
qualities,  but  is  higher  in  the  scale  of  fixed  carbon. 

Lignite  or  Brown  Goal  "occurs  in  the  more  recent 
geological  formations.  The  processes  of  mineraliza- 
tion having  been  less  completely  effected  than  in  the 
older  coals,  they  exhibit  their  vegetable  structure 


266          PROSPECTING  AND   VALUING  MINES. 

more  completely,  and  as  an  effect  of  the  same  cause 
they  retain  a  much  larger  proportion  of  the  volatile 
matters.  In  color  they  vary  from  brown  to  pitch 
black.  Their  luster  is  generally  dull,  but  sometimes 
resinous;  the  fracture  is  various.  They  burn  readily 
with  a  dull  flame,  emitting  much  srnoke,  and  an  un- 
pleasanfc  odor.  In  consequence  of  the  small  propor- 
tion of  carbon  and  the  large  quantity  of  water  which 
the3r  contain,  the  brown  coals  do  not  possess  great 
heating  power.  They  are  largely  developed  in  the 
western  States  of  America.  On  account  of  the  large 
amount  of  water  they  'slack'  into  small  fragments 
when  exposed  to  the  air  and  sun,  the  large  blocks  soon 
showing  a  multitude  of  cracks/' 

IMPURITIES  IN  GOAL. — -In  all  the  foregoing  remarks 
the  coal  is  supposed  to  be  free  from  impurities,  but  as 
a  matter  of  fact  this  is  seldom  the  case.  "The  impuri- 
ties may  be  classed  as  essential  and  accidental;  the 
former  being  those  which  entered  into  the  composition 
of  the  vegetable  substances  from  which  the  coal  was 
formed,  and  the  latter  those  which  have  been  inter- 
mixed with  these  substances.  The  essential  impurities 
consist  of  silica,  alumina,  lime,  magnesia  and  oxide  of 
iron,  to  which  may  be  added  water.  The  accidental 
impurities  may  consist  of  any  substance  other  than 
the  elements  mentioned.  Some  of  these  have  been  in- 
troduced by  the  infiltration  of  water  holding  the  sub- 
stances in  solution.  In  general  the  accidental  impuri- 
ties consist  of  earthy  matters,  which  were  probably 
deposited  from  water  flowing  among  the  coal  vegeta- 
tion, or  blown  thither  by  the  winds.  The  quantity  of 
earthy  impurities  present  in  any  given  sample  of  coal 
is  estimated  by  weighing  the  ash  after  combustion. 
When  the  weight  of  the  ash  so  left  does  not  exceed 
5%  of  that  of  the  coal,  the  latter  is  considered  very 
pure.  Above  that  proportion  it  begins  to  lose  in 
quality  and  becomes  hard  and  shaly  in  structure. 

"A  common  impurity  is  iron  pyrite,  or  sulphuret  of 


COAL.  267 

iron,  a  substance  known  to  coal  miners  as  'brasses.' 
Pyrite  occurs  sometimes  as  a  deposit  filling  the  cracks 
and  fissures  in  the  coal;  sometimes  as  thin  beds.  It  is 
not  infrequently  met  with  running  with  a  line  of  part- 
ing, or  it  occurs  as  crystals  disseminated  throughout 
the  mass;  and  more  often  as  minute  particles  imper- 
ceptible to  the  naked  eye.  The  presence  of  iron. pyrite 
detracts  greatly  from  the  value  of  coal  by  rendering  it 
unsuitable  for  many  important  purposes.  Coal  con- 
taining this  mineral  is  totally  unfit  for  [iron  and  steel] 
metallurgical  purposes  [though  available  for  other 
metallurgical  uses,  as  in  roasting  and  smelting  certain 
metals],  and  it  cannot  be  burned  anywhere  in  contact 
with  iron  without  serious  injury  to  the  latter.  Hence 
it  cannot  be  employed  for  the  generation  of  steam,  as 
its  corroding  action  would  rapidly  destroy  the  fire- 
grating  and  the  lower  plates  of  the  boiler.  Moreover, 
pyrite  is  decomposed  by  moisture  and  converted  into 
a  sulphate,  and  the  expansion  which  takes  place  dur- 
ing the  process  tends  to  break  the  coal  into  very  small 
lumps  and  even  to  powder.  This  decomposition  is 
often  accompanied  by  great  heat,  and  spontaneous 
combustion  is  not  infrequently  occasioned  thereby. 
Heaps  of  brassy  small  coal  and  rubbish  lying  as  refuse 
on  the  pit  bank  often  take  fire  from  this  cause  in  wet 
weather,  and,  which  is  of  far  more  disastrous  conse- 
quence, the  exposed  coal  in  the  workings  will  some- 
times become  ignited." 

While  no  coal  is  free  from  impurities,  the  variation 
is  great  both  as  to  the  amount  of  ash  left  after  burn- 
ing and  of  water.  From  the  nature  of  the  origin  of 
coal,  as  has  been  already  seen,  there  must  be  a  thin 
edge  to  the  bed  entirely  round  its  circumference,  and 
this  will  naturally  contain  a  larger  percentage  of  im- 
purities than  the  central  mass,  "where  they  may  be 
scattered  through  the  entire  thickness  of  the  seam  or 
consist  of  thin  alternate  layers.  Sometimes  one  or 
more  of  these  layers  will  extend  over  a  large  area  and 


268         PROSPECTING  AND   VALUING  MINES. 

frequently  assist  materially  in  mining  the  coal.  In 
such  cases  the  upper  seam  may  have  quite  a  different 
character  to  the  lower  one  and  may  be  mined  sepa- 
rately. 

TEST  FOB  COKING  QUALITIES. — Some  coals  -which 
appear  to  contain  the  requisite  ingredients  to  make 
good  coke  refuse  to  coke  except  under  particular 
treatment,  and  only  a  series  of  analyses,  followed  by 
working  tests,  can  determine  tha  ultimate  value  of  a 
field,  or  to  what  purpose  the  product  may  be  best 
adapted;  but  the  prospector  may  readily  ascertain  for 
himself  by  the  camp  fire,  whether  his  find  comes 
within  the  coking  series  by  the  following  means: 
Take  a  clay  pipe  with  a  moderately  long  stem ;  fill  the 
bowl  with  clean  powdered  coal,  and  then  carefully 
lute,  or  stop  the  top  with  stiff,  well-worked  clay.  It 
is  not  advisable  to  fill  the  bowl  too  full,  as  if  the  coal 
should  prove  to  coke,  it  will  swell  on  heating,  and 
raise  the  clay  cap,  admitting  air,  and  the  experiment 
will  be  a  failure,  as  the  coal  will  take  fire.  When  pre- 
pared, place  the  bowl  of  the  pipe  in  the  fire,  heating 
it  gently  at  first  to  dry  the  clay  without  cracking,  and 
then  more  rapidly  to  a  white  heat.  Smoke  and  gas 
will  be  given  off  (through  the  stem),  which  will  burn 
freely,  being  made  up  of  the  volatile  matter,  water 
and  sulphur.  When  this  ceases  the  operation  is  com- 
plete. Take  the  pipe  from  the  fire,  and  if  the  coal 
will  coke,  the  bowl  will  be  found  to  contain  a  solid 
mass  of  ccke  of  a  bright  dark  gray  color,  hard  and 
compact,  if  good;  but  easily  crumbling  to  powder  if 
of  poor  quality.  If  the  luting  or  stopper  of  clay  has 
cracked  it  may  be  partially  burned  up,  but  a  few  ex- 
periments will  easily  give  the  requisite  skill  to  make 
the  test.  A  large  portion  (practically  all)  of  the  ash, 
of  course,  goes  into  the  coke. 

The  ash  is  determined  by  weighing  the  earthy 
matter  left  after  burning  a  definite  weight  of  dry  coal 
in  the  open  air  (by  which  the  carbon  as  well  as  the 


CO  A  L.  269 

volatile  matter  is  consumed),  and  calculating  the  per- 
centage. Analysis  alone  can  determine  this  accu- 
rately and  furnish  tne  information  whether  it  is  a 
high  or  low  grade  coal,  in  case  it  refuses  to  coke. 

COMMEECIAL  VALUE. — The  prospector's  interest  in  a 
coal  discovery  centers  in  the  question  whether  it  will 
become  a  business  success  on  development.  This 
depends  on  the  number,  thickness  and  dip  of  the 
workable  beds;  on  an  abundant  supply  of  cheap  labor, 
to  keep  the  cost  of  mining,  sorting  and  washing  at  a 
low  figure;  cheap  transportation  by  land  or  water; 
and  freedom  from  competition  with  coals  of  its  own 
class,  thus  filling  a  vacant  place  in  the  market.  Many 
or  all  of  these  items  may  be  largely  modified  if  the 
coal  is  found  in  a  region  otherwise  largely  devoid  of 
fuel,  as  many  of  our  interior  mining  districts,  in 
which  the  price  might  be  greatly  enhanced,  and  the 
product  yet  have  a  ready  sale:  but  the  conditions  be- 
come emphasized,  especially  as  regards  coal  for  domes- 
tic purposes,  in  densely  wooded  districts  like  western 
Washington. 

But  with  all  conditions  apparently  favorable,  the 
exploration  of  the  field  may  result  in  failure,  from 
excessive  and  unexpected  "faulting"  of  the  coal  largely 
increasing  the  cost  of  working;  by  the  intrusion  of 
eruptive  rocks  into  the  coal  seams,  destroying  the 
coal ;  by  a  change  in  the  character  of  the  coal ;  by  the 
thinning  out  of  the  beds;  or  the  opening  of  other 
mines  better  located  with  regard  to  some  item  which 
gives  them  an  advantage  in  the  market. 

PROSPECTING. — There  is  not  much  to  be  said  on  this 
subject.  The  first  discovery  is  likely  to  be  purely  ac- 
cidental, but  when  made  a  few  simple  rules  will  assist 
in  tracing  the  outcrop.  The  first  thing  is  to  get  a 
good  knowledge  of  the  rocks  between  which  the  coal  is 
found  and  their  relation  to  other  rocks  above  and  below 
them,  keeping  a  sharp  lookout  while  doing  this  for 
any  fossils  such  as  shells  or  plants.  After  acquiring 


270         PROSPECTING  AND  VALUING  MINES. 

this  knowledge,  the  search  must  be  confined  to  the 
region  occupied  by  these  floor  and  roof  rocks,  and  the 
knowledge  gained  of  the  associated  rocks  will  tell  the 
searcher  in  which  direction  he  must  look,  if  he  acci- 
dentally has  wandered  beyond  the  limits  of  the  coal- 
bearing  series,  because,  from  the  way  in  which  the 
beds  were  formed  originally,  they  are  now  found  more 
or  less  parallel  to  the  junction  of  two  different  kinds 
of  rock. 

If  the  country  has  been  much  tilted  the  outcrop 
may  follow  quite  a  wavy  line  or  even  apparently  run 
in  a  semicircle,  but  having  by  the  means  just  stated 
defined  the  limits  of  the  area  in  which  coal  is  likely 
to  be  found,  the  search  may  be  continued  by  follow- 
ing up  the  ravines  which  cut  this  formation.  In  a 
densely  wooded  country  this  kind  of  exploration  is 
difficult,  but  as  the  coal  is  softer  than  the  rocks  in 
which  it  is  found,  tljere  is  usually  a  sharp  break  or 
drop  in  the  bed  of  the  ravine  at  the  point  where  the 
coal  crosses,  and  all  such  places  should  be  carefully 
examined.  Beyond  this  the  prospector  must  use  his 
own  judgment. 

As  coal  suffers  from  exposure  to  the  elements,  it  is 
likely  that  the  outcrop  will  be  inferior  to  the  coal 
found  at  a  little  depth  below,  but  whenever  the  roof 
and  floor  become  solid  and  show  no  signs  of  decay,  the 
coal  there  found  may  be  taken  as  a  general,  but  very 
rough,  sample  of  the  deposit. 

Provided  all  the  surroundings  appear  satisfactory  a 
complete  series  of  borings  should  be  made  to  prove  the 
condition  of  the  beds  as  regards  "faulting, "  but  at 
this  point  the  work  of  the  prospector  ends,  and  that  of 
the  engineer  begins. 


CHAPTER  XVI. 
GOLD  GRAVEL  DEPOSITS. 

GRAVEL  MINING  or  washing  is  carried  on  to  obtain 
placer  gold,  platinum,  tin,  diamonds  and  some  other 
less  important  substances,  which  are  found  during  the 
search  for  the  more  valuable  ones.  When  the  water 
used  in  the  process  is  applied  under  pressure,  the  term 
"hydraulic  mining"  is  applied  to  the  operation. 

The  deposits  operated  upon  may  be  glacial  drift; 
the  beds  and  hillsides  of  modern  streams,  which  are 
generally  called  "placers,"  and  the  operation  "placer 
mining;"  or  the  gravel  accumulated  in  the  beds  of 
ancient  streams,  long  since  dry,  and  not  infrequently 
located  high  on  the  mountain  sides  above  all  the  pres- 
ent rivers,  may  be  attacked  by  hydraulic  methods, 
when  not  covered  with  a  lava  cap;  or  "drifted"  by 
means  of  tunnels,  in  a  manner  similar  to  coal  mining, 
when  the  cap  of  the  mountain  is  too  hard  to  be 
removed  economically,  or  the  top  gravel  too  poor  to 
pay  for  washing,  or  water  too  scant  in  supply  or  with 
too  small  a  head  or  pressure  to  admit  of  hydraulicking. 
The  working  of  ordinary  placers  by  ground  sluices  or 
by  sluice  boxes  is  so  well  .mown  that  it  is  not  neces- 
sary here  to  enter  into  any  details. 

In  studying  gravel  deposits  we  must  remember  that 
the  laws  governing  the  operations  of  nature  have  been 
the  same  for  all  time;  that  the  forces  have  been  the 
same,  though  they  may  have  operated  with  greater 
activity ;  and  that  any  explanation  of  the  phenomena 
which  is  not  in  strict  accordance  with  these  laws  must 


272         PROSPECTING  AND   VALUING  MINES. 

inevitably  be  erroneous  and  defective.  This  caution 
is  the  more  necessary  as  we  have  to  deal  largely  in  our 
explorations  with  things  that  we  cannot  see  and  can 
only  base  our  surmises  as  to  their  condition  on  the 
laws  which  we  know  to  govern  the  same  circumstances 
in  the  world  which  is  open  to  our  inspection.  Any 
proposition  which  is  in  direct  opposition  to  these  laws 
should  be  laid  aside  promptly  as  worthless.  The 
importance  of  this  is  especially  apparent  in  the  open- 
ing of  "drift"  mines. 

ORIGIN  OF  GRAVEL  DEPOSITS. — All  accumulations  of 
gravel  and  sand  have  been  made  by  the  action  of 
water,  either  as  running  streams  or  sea  waves,  or  by 
ice  as  glaciers  and  icebergs,  and  result  from  the  wear- 
ing away  of  rocks  by  the  action  of  the  air  or  rain  or 
frost,  or  all  three  combined.  The  nature  of  their  con- 
tents must  therefore  depend  on  the  character  of  the 
rocks  which  have  been  destroyed  and  the  width,  depth 
and  velocity  of  the  streams  which  carried  the  material 
to  its  resting  place,  or  the  area  over  which  ice  sheets 
and  glaciers  or  floating  ice  could  carry  its  burden  of 
soil  and  rocks  before  melting  and  depositing  its  load. 

As  we  have  seen  in  studying  the  filling  of  mineral 
veins,  the  minerals  are  disseminated  through  a  variety 
of  rocks,  and  the  presence  of  veins  is  not  necessary,  as 
is  so  generally  supposed,  to  "feed"  the  stream.  When 
a  stream  ceases  to  show  gold  in  the  bed  on  following 
it  upward,  it  does  not  follow  that  there  must  be  a  rich 
vein  in  that  vicinity,  for  which  we  constantly  find  the 
miners  searching;  it  may  be  simply  an  intimation  that 
the  upper  limit  of  the  gold-bearing  rocks  has  been 
reached.  We  can  indeed  have  good  placer  diggings 
in  regions  where  well-defined  veins  are  scarce.  If 
we  once  thoroughly  realize  this  general  distribution 
of  gold  in  certain  belts  of  rock,  the  origin  of  gravel 
deposits  carrying  gold,  tin  or  platinum  becomes  much 
more  easily  intelligible. 

When  the  rock  is  decomposed  by  the  ordinary  action 


GOLD  GRA  VEL  DEPOSITS.  273 

of  frost  or  air  and  rain,  the  detached  particles  are  con- 
stantly descending  by  the  steepest  line,  under  the 
action  of  gravity  or  water,  and  this  is  usually  more  or 
less  at  right  angles  to  the  stream  into  which  they 
finally  find  their  way.  During  this  descent  the  par- 
ticles of  gold  suffer  but  little  abrasion,  as  their  prog- 
ress is  excessively  slow,  and  they  undergo  no  sorting 
into  sizes,  other  than  what  would  result  from  the 
greater  momentum  of  the  larger  particles,  causing 
them  to  travel  further  on  a  steep  side  hill  where  but 
little  surface  water  and  rivulets  acted;  but  if  there 
were  much  water  coming  down  the  side  hills, the  reverse 
might  occur,  the  larger  gold  particles  resisting  more 
than  the  light  flaky  ones.  On  entering  the  water  their 
fate  depends  on  the  depth  of  water  and  the  velocity  of 
the  stream.  If  the  latter  is  great,  the  finer  flaky  par- 
ticles, which  even  in  still  water  descend  to  the  bottom 
very  slowly,  will  be  swept  away  with  the  sand  on  their 
seaward  journey,  only  the  heavier  pieces  reaching  the 
bottom,  where  they  will  continue  to  sink  into  the  river 
bed  by  their  superior  weight  as  long  as  the  surface  is 
very  soft  or  slightly  agitated.  The  less  the  velocity, 
the  smaller  will  be  the  amount  thus  swept  away.  In 
cases  where  the  gold  has  not  been  much  subject  to  the 
action  of  water  for  continuous  periods,  it  may  retain 
its  crystallized  or  angular  form,  and  this  is  usually  an 
indication  of  the  vicinity  of  a  vein,  especially  if  por- 
tions of  quartz  are  still  attached  to  the  specimens. 
The  smoothing  and  flattening  of  nuggets  and  grains  of 
river  gold  is  probably  due  to  a  large  extent,  if  not  alto- 
gether, to  the  impact  of  heavy  rocks  and  the  polishing 
action  of  sand  and  gravel  as  they  are  swept  over  it  in 
the  river  bottom,  just  as  such  material  polishes  and 
wears  away  the  angles  of  bowlders  or  solid  masses  pro- 
jecting from  the  bottom  of  the  stream.  It  does  not 
seem  probable  that  the  coarse  gold  has  ever  traveled 
very  far  from  the  point  where  it  first  found  lodgment 
in  the  river,  but  the  very  finest  particles  may  be  trans- 


274        PROSPECTING  AND   VALUING  MINES. 

ported  many  miles.  Gold  derived  from  the  decay  of 
either  iron  or  arsenical  pyrites  rnay  be  so  excessively 
fine  that  it  will  never  find  a  lodgment  on  the  bottom 
until  the  sediment  with  which  it  is  mixed  reaches 
quiescent  or  perfectly  tranquil  waters. 

RIVER  DEPOSITS. — 'All  rivers  and  streams  may  be 
compared  to  immense  sluice  boxes  in  which  the  heavier 
particles  have  been  retained,  and  the  lighter  ones 
washed  away,  while  nature  has  been  carving  out  the 
river  basins  with  all  the  forces  at  her  command,  pre- 
senting for  our  final  clean  up  the  contents  of  an 
immense  mass  of  material  so  inexpressibly  poor  in 
gold,  platinum,  tin,  etc.,  that  human  efforts  could  not 
have  undertaken  the  task.  Some  idea  of  the  extent  of 
this  concentration  may  be  obtained  when  we  remem- 
ber that  we  have  absolute  evidence  that  some  of  the 
river  channels  in  California  have  been  cut  down  fully 
2,000ft.  below  the  surface  as  it  exists  to-day.  In  such 
a  valley  with  a  width  of  6,000  ft.  from  rim  to  rim, 
6,000,000  cu.  ft.  of  rock  have  bean  removed  (6,GOOX 
2,000-=-2)  to  carve  out  one  running  foot  of  its  length, 
and  all  that  remains  may  be  a  deposit  400  ft.  wide  by  an 
average  depth  of  20  ft.,  or  8,000  cu.  ft.  to  the  running 
foot  of  the  ralley,  or  in  other  words  222,222  cu.  yds. 
have  been  concentrated  down  to  about  300  in  round 
numbers  (say  740:1).  If  the  value  of  this  be  $1  per 
yd.  the  original  material  would  only  have  contained 
about  one  and  a  third  mills  in  the  same  quantity 
($0.00135). 

During  this  process  a  portion  of  the  finer  gold  has 
been  carried  down  the  stream  to  flatter  regions  by  the 
strength  of  the  current,  but  the  coarser  has  been 
retained,  probably  not  far  from  its  source,  the  extent 
of  the  deposit  varying  considerably  with  the  character 
of  the  bottom  of  the  channel,  the  bowlders  in  which 
act  the  part  of  riffles  or  lining  in  the  artificial  sluice 
box. 

Modern  Streams.—^ In  the  case  of  the  modern  moun* 


GOLD  GRAVEL  DEPOSITS.  275 

tain  streams,  the  velocity  arid  quantity  of  water  have 
been  so  adjusted  to  the  amount  of  material  brought 
down,  that  the  bulk  of  the  finer  debris  or  waste  has 
been  carried  down  to  the  valleys  below,  leaving  only 
the  coarser  gravel  and  bowlders  in  the  beds  of  the 
ravines  filled  in  with  a  certain  percentage  of  fine  ma- 
terial in  the  interspaces,  making  the  deposits  compar- 
atively shallow  and  rich,  and  there  does  not  appear  to 
have  been  much  change  from  time  to  time  in  the  con- 
ditions under  which  they  were  made. 

Ancient  Ewers. — When  we  come  to  study  the 
ancient  or  buried  streams,  as  they  existed  prior  to  the 
last  great  outbreak  of  lavas,  in  which  the  deposits  are 
sometimes  400  ft.  thick  or  over,  we  shall  find  evi- 
dences of  great  alterations  in  the  flow  of  water  from 
time  to  time,  and  the  character  and  quantity  of  the 
material  carried  by  it  in  suspension.  If  we  trace  the 
history  of  one  of  these  old  river  channels,  as  read  by  the 
records  it  contains  within  itself,  construed  by  the  laws 
of  nature  in  operation  to-day,  as  in  the  past,  we  shall 
get  a  clearer  idea  of  their  structure  than  in  any  other 
way  and  be  better  prepared  to  open  them  for  success- 
ful mining. 

Bedrock;  Eim;  Grade. — The  rock  on  which  the 
gravel  deposits  lie  is  called  the  "bedrock  "  (see  pi.  10, 
figs.  1  to  6),  and  the  point  where  the  bedrock  and  gravel 
or  lava  are  seen  in  contact  on  the  surface  the  "rim," 
as  in  pi.  10,  fig.  4,  a,g;  fig.  5,  a.  The  inclination  of 
the  bottom  of  the  stream  in  the  direction  of  its  flow 
is  known  as  the  "grade"  of  the  channel.  By  com- 
parison with  known  mountain  ranges,  it  will  be  seen 
that  all  streams  have  steep  grades  near  their  sources, 
becoming  flatter  and  flatter  as  they  approach  the  low- 
land valleys. 

Bottom  Gravels. — The  first  stage  was  similar  to  the 
conditions  surrounding  our  modern  streams.  The 
wearing  away  of  the  hills  was  carried  on  comparatively 
slowly,  the  streams  were  of  moderate  velocity,  carry- 


2?6        PROSPECTING  AND  VALUING  MINES. 

ing  off  the  waste  and  leaving  the  coarse  gravel  and 
gold  in  the  river  beds.  Large  quantities  of  material 
brought  down  in  flood  time  were  gradually  panned  out 
during  the  drier  seasons,  as  we  know  by  the  thin 
layers  of  iron  sand,  such  as  we  see  cleaned  up  by  the 
lap  of  the  stream  on  our  present  river  banks  and  sea 
beaches,  leaving  the  contained  gold  to  enrich  the  bot- 
tom deposits.  In  this  way  the  so-called  " bottom" 
gravels,  which  are  the  exact  counterpart  of  the  modern 
placers,  were  formed,  by  the  alternate  flood  deposits 
and  slackwater  panning.  These  bottom  gravels  are 
usually  the  only  ones  which  will  pay  for  the  slow 
process  of  drifting;  and  sometimes,  when  too  poor  for 
this  method  of  working,  the  entire  "top  dirt"  has  to 
be  removed,  even  if  it  barely  cover  expenses. 

The  Deep  Beds. — Then  commenced  a  change  in  the 
surroundings.  The  quantity  of  sediment  sent  down 
had  been  so  great  that  the  streams  at  the  mouths  of 
the  mountain  valleys  became  filled  up  and  the  sedi- 
ments began  to  accumulate  in  the  valleys  themselves, 
and  from  that  time  the  material  deposited  assumed  a 
flat  grade,  and  the  filling  up  of  the  bed  of  the  stream 
proceeded  at  a  rapid  rate,  creeping  upward  as  the 
lower  portions  became  more  and  more  choked,  until 
in  some  cases  we  find  the  thickness  of  these  beds  run- 
ning up  into  the  hundreds  of  feet.  The  gold  in  such 
material  is  naturally  fine,  and  not  having  undergone 
the  process  of  concentration  to  such  an  extent  as  the 
bottom  gravel  is  much  less  in  quantity  for  equal  bulk 
of  material;  but  there  is  no  sharply  defined  line  be- 
tween the  two,  although  the  depreciation  takes  place 
rapidly  until  the  general  average  value  of  the  upper 
fine  beds  is  reached.  This  results  from  the  fact  that 
there  is  to  some  extent  a  combination  of  both  condi- 
tions at  or  near  the  point  where  the  flat  grade  of  the 
valley  met  the  steeper  slope  of  the  mountain  stream. 
As  the  valley  filled  up  the  river  channel  naturally  be- 
came wider,  the  sheet  of  water  thinner  and  in  conse- 


GOLD  GRA  VEL  DEPOSITS.  277 

quence  less  and  less  able  to  carry  any  burden  in  sus- 
pension, and  it  is  easy  to  picture  a  wide  sandy  bottom 
with  changing  channels,  bars  and  stagnant  pools  ob- 
structed by  snags  and  log  jams.  All  the  conditions 
are  beautifully  shown  in  the  deep  gravel  workings 
at  Sailor  Flat  in  Nevada  County,  Cal.  PI.  12,  fig.  7, 
shows  a  portion  of  the  gravel  bank  at  this  place,  and 
the  constant  changes  of  the  channels  can  be  read  in 
the  various  deposits  of  sand  and  gravel  lying  uncon- 
formably  on  each  other.  The  black  marks  in  this 
figure  show  the  position  of  pieces  of  petrified  wood, 
which  is  found  in  enormous  quantities  in  every  con- 
ceivable form  of  petrifaction.  Sometimes  the  trees 
are  imbedded  singly;  at  other  points  they  have  ac- 
cumulated on  bars  aud  are  massed  together  as  we  see 
them  in  modern  streams  after  floods.  In  the  shallow 
pools,  the  falling  leaves  have  accumulated  in  the  fine 
silt  or  mud,  which  now  splits  in  very  thin  layers,  and 
reveals  a  wonderful  variety  of  leaves,  the  imprints  of 
which  are  in  an  excellent  state  of  preservation. 

That  there  were  occasional  periods  of  drought  when 
the  water  was  comparatively  free  of  sediment,  yet  with 
a  velocity  sufficient  to  pick  up  and  remove  the  finer 
sand  to  a  certain  extent,  is  shown  by  the  thin  beds  of 
fine  gravel  which  can  be  seen  on  the  face  of  the  bank, 
and  which  by  their  superior  richness  indicate  a  certain 
amount  of  concentration,  as  in  the  bottom  gravels.  In 
a  few  cases  these  beds  have  become  sufficiently  thick 
and  enriched  to  pay  for  drifting,  as  in  the  case  of  tbe 
Breece  &  Wheeler  mine  in  California,  of  which  a  gen- 
eralized cross  section  is  shown  in  pi.  11,  fig.  2.  The 
upper  tunnel  was  run  on  such  a  deposit,  so  cemented 
together  by  the  iron  which  remained  among  the 
gravel,  as  a  part  of  the  concentrates,  that  it  had  to  be 
crushed  in  a  mill  to  save  the  gold.  On  pi.  10.  fi^s.  1, 
2  and  3,  the  so-called  top  dirt  is  shown  by  c,  the  bot- 
tom dirt  being  indicated  by  the  solid  black  at  g.  The 
modern  placer  deposits  are  shown  at  ete,e. 


278         PROSPECTING  AND  VALUING  MINES. 

Pipeclay. — The  beginning  of  the  third  stage  com- 
mences with  the  renewed  volcanic  activity.  The  de- 
position of  sand  and  gravel  ceased  and  immense  beds 
of  clay,  called  by  the  miners  " pipeclay,"  sometimes 
reaching  a  thickess  of  200  ft,  as  at  Cherokee  Flat  in 
Butte  County,  were  laid  down.  Afc  other  points  we 
have  deposits  of  rounded  bowlders  like  cobblestones, 
and  it  is  not  unlikely  that  these  deposits  were  derived 
from  the  earlier  outbreaks  of  the  volcanoes,  accom- 
panied by  excessive  rainfall,  which  washed  the  ejected 
matter  into  the  ravines,  the  finer  material,  as  in  all 
other  cases,  being  carried  furthest  from  its  source. 
Most  of  the  bowlders  in  ordinary  placer  ground  are 
merely  waterworn  fragments  of  local  rocks;  the  large 
proportion  of  quartz  bowlders  being  due  to  their  hard- 
ness. It  is  certain,  however,  that  immediately  succeed- 
ing these  bowlders  and  clay,  immense  outbursts  of 
lava  poured  into  the  river  bottoms  and  filled  them 
from  bank  to  bank.  A  case  where  a  bed  of  sinter 
(volcanic  ash)  separates  unconformable  gravel  beds  is 
shown  in  pi.  12,  fig.  6,  where  the  sinter  bed  appears 
to  have  been  tilted  after  deposition. 

Lava  Cap. — Some  of  the  lava  beds  are  over  100  ft. 
in  thickness  and  form  to-day  conspicuous  objects  in 
the  landscapes  of  the  gold  regions  of  California,  where 
they  cap  hills  called  "table  mountains,"  from  their 
nearly  level  summits  as  seen  against  the  sky,  and  their 
precipitous  sides.  In  pi.  10,  figs.  1,  2  and  3,  the  pipe- 
clay is  shown  by  b  and  the  lava  cap  by  a.  With  the 
formation  of  the  lava  cap  the  process  of  filling  was 
completed.  PI.  10,  fig.  1,  shows  the  order  of  succes- 
sion— -bottom  gravel,  g;  fine  gravel  and  sand,  c;  pipe- 
clay, b;  lava,  a.  The  dark  shaded  portion  shows  a 
cross  section  of  a  mountain  with  its  ravines  as  they 
exist  to-day.  The  dotted  lines  m,m,  show  the  hills 
on  either  side  of  the  valley  as  they  existed  during  the 
process  of  filling,  and  the  horizontal  dotted  lines  r,s,t, 
the  continuation  of  the  beds  a,6,c,  before  they  were 
worn  away. 


GOLD  OR  A  VEL  DEPOSITS.  279 

Modern  Forms. — The  carving  of  the  country  to  its 
present  form  then  began.  The  river  waters  on  resum- 
ing their  sway  were  diverted  into  new  channels,  and 
in  most  cases  two  streams  were  formed  out  of  the  orig- 
inal one.  When  lava  Hows  into  a  confined  channel 
such  as  a  valley,  the  surface  and  sides  of  the  stream 
in  contact  with  the  rocks,  and  especiallj*  the  thinner 
edges,  cool  more  rapidly  than  the  central  core,  which, 
remaining  in  a  plastic  condition,  is  liable  from  the 
pressure  behind  to  break  the  upper  crust.  This  is 
consequently  piled  up  in  the  center  of  the  flow  in 
rugged  masses  with  a  higher  elevation  than  the  sides. 
In  this  way  there  is  formed  a  depression  on  each  side 
of  the  flow  next  to  the  valley  walls,  each  of  which  be- 
comes a  watercourse,  indicated  by  the  arrows  in  fig. 
1.  Owing  to  the  superior  hardness  of  the  lava  the 
cutting  away  of  the  new  channels  took  place  largely  at 
the  expense  of  the  rocks  forming  the  walls  of  the 
valley.  By  degrees  these  were  eaten  away  below  the 
level  of  the  under  side  of  the  lava,  when  the  process 
went  on  more  rapidly  in  the  underlying  clay  and 
gravel,  which  on  being  undermined  allowed  the  ^a 
to  break  off  in  vertical  faces  forming  the  characteristic 
bluffs  of  the  gold  regions.  While  this  process  was 
going  on  large  quantities  of  the  finer  gravel  of 
the  original  deposits  were  carried  down  to  lower 
regions,  taking  with  it  the  finest  of  the  gold,  the 
coarse  remaining  behind,  and  new  placers  were  form- 
ing. We  have  evidence  that  there  were  two  outbursts 
of  lava,  producing  similar  results.  In  the  lower  val- 
leys the  lava  caps  are  entirely  basaltic,  but  in  the 
higher  regions  the  first  eruptions  were  either  trachytic 
or  rhyolitic.  Both  eruptions  are  well  shown  in  Plumas 
Co'unty,  as  in  pi.  10,  fig.  1.  When,  after  the  trachyte 
outburst,  the  cutting  of  the  new  valleys  had  proceeded 
to  about  half  its  ultimate  extent,  the  basalt  outbreak 
occurred  and  invaded  some  but  not  all  of  the  streams. 
In  this  case  the  gravel  contains  pebbles  of  the  lava  c<>v- 


280         PROSPECTING  AND   VALUING  MINES. 

ering  the  older  channel,  a,&,c,(/,  along  with  the  quartz 
gravel  which  is  characteristic  of  both,  but  the  lava  cap 
is  au  exceedingly  hard,  heavy,  compact,  black  iron- 
like  basalt,  while  the  cap  of  the  older  channels  is  a 
light-colored  gray  or  reddish  trachyte,  much  lighter 
and  coarser  in  grain  than  the  basalt,  and  very  harsh 
to  the  touch  on  a  newly  broken  face.  Being  much 
softer  than  the  basalt  and  less  liable  to  take  columnar 
forms,  it  seldom  presents  such  conspicuous  bluffs  as 
the  basalt.  In  some  cases  the  basalt  lies  directly  on 
the  gravel;  in  others  there  is  the  usual  bed  of  pipe- 
clay. If  this  is  absent  we  may  presume  that  the 
region  was  near  the  source  of  the  lava  flow,  and  that 
the  material  forming  the  clay  bed  had  been  washed 
down  to  the  lower  country  or  had  not  been  ejected  in 
large  quantities.  The  clay  beds  under  the  basalt  at 
Cherokee  Flat  in  the  foothills  of  the  Sacramento  valley 
are  very  thick,  while  in  Onion  valley,  near  the  summit 
of  the  Sierra  Nevada,  at  an  altitude  of  5,000  ft.,  they 
are  either  very  thin  or  absent.  That  the  eruption  of 
the  basalt  was  later  than  the  formation  of  the  older 
gravel  beds  is  absolutely  proved  by  the  occurrence  in 
the  Laporte  region,  Plumas  County,  which  is  located 
on  a  trachyte-covered  channel  of  great  length  and 
prominence,  of  a  basalt  cone  overlying  a  bed  of  gravel, 
the  pipe  or  neck  of  which  was  penetrated  by  one  of  the 
deep  tunnels,  and  the  gravel  bed  "drifted"  all  around 
it,  some  of  the  gravel  being  even  surrounded  by  thin 
sheets  of  lava  at  the  outer  circumference  of  the  neck 
which  formed  the  vent.  At  this  particular  locality  the 
trachyte  cap  had  been  eroded.  The  structure  is  shown 
in  pi.  10,  fig.  6,  where  a  is  the  gravel  and  b  the  lava 
cone  with  its  neck  or  pipe  ascending  through  the  bed- 
rock and  gravel. 

Since  the  basalt  outburst,  which  Was  of  enormous 
extent,  covering  hundreds  or  even  thousands  of  square 
miles  in  California,  Oregon  and  Washington,  there 
seems  to  have  been  no  serious  volcanic  disturbance,  and 


GOLD  GRAVEL  DEPOSITS.  281 

the  denudation  went  steadily  on  up  to  modern  times, 
leaving  a  mountain  range  in  the  case  of  each  flow,  of 
which  we  have  a  plan  in  pi.  11,  fig.  1,  which  repre- 
sents two  modern  streams  B,E,  and  the  buried  ancient 
river  8U,  with  those  portions  of  its  lateral  streams 
which  have  not  been  worn  away  in  the  general  denuda- 
tion. L  represents  the  lava  and  pipeclay  capping;  G 
the  gravel,  and  the  heavy  black  lines  that  portion 
which  is  known  as  the  bottom  gravel  and  is  suitable 
for  drifting.  As  the  denudation  has  not  progressed 
evenly,  it  may  happen  that  the  gravel  at  some  points 
has  not  been  exposed,  and  the  lava  apparently  lies  on 
the  bedrock,  as  at  U. 

"Over/lows." — In  other  places  it  may  be  exposed  on 
ona  or  both  sides  of  the  ridge,  or  the  lava  cap  may  have 
entirely  disappeared,  as  at  (7,  showing  the  gravel  on 
the  surface  all  the  way  across  the  dividing  ridge.  The 
richer  bottom  gravel  found  in  the  lateral  branches  of 
the  stream  will  naturally  be  exposed  as  at  T,  T.  A 
common  term  for  these  exposures  is  an  "overflow,"  as 
though  the  gravel  had  been  squeezed  out  of  the  hill, 
but  that  this  expression  is  erroneous  is  shown  from  the 
fact  chat  the  grade  or  inclination  of  the  bedrock  dips 
into  the  hill,  as  shown  in  pi.  10,  fig.  5,  where  a 
is  the  so-called  overflow  and  g  the  main  channel 
to  which  it  leads.  The  only  exception  to  this  rule 
is  where  a  remnant  of  the  head  of  one  of  these  lateral 
branches  is  left  on  the  other  side  of  the  modern  ravine, 
which  has  cut  the  lateral  in  two  without  removing  the 
upper  portion.  Unless  this  lateral  was  a  large  stream, 
the  gravel  left  will  be  only  a  small  patch.  If  a  large 
stream  it  may  present  all  the  features  of  the  main  chan- 
nel if  it  happened  to  be  covered  with  lava  (which  does 
not  necessarily  follow). 

Laterals. — We  also  frequently  hear  miners  speak  of 
two  or  more  channels  in  the  hill.  Such  a  condition  of 
things  is  against  all  probability;  the  dividing  of  a  stream 
into  several  branches  being  almost  exclusively  confined 


282         PROSPECTING  AND  VALUING  MINES. 

to  those  portions  which  have  a  flat  grade,  and  does 
not  occur  where  the  grades  are  such  as  we  find  in 
mountain  regions.  What  does  occur  is  shown  on  the 
line  OP,  pi.  11,  fig.  1,  where  if  OP  were  a  tunnel  it 
would  cut  two  bodies  of  gravel,  but  they  would  be  only 
branches  of  the  same  stream,  the  first  one  encountered, 
if  the  tunnel  started  at  0,  having  a  steeper  grade  than 
the  second,  as  lateral  branches  of  a  river  have  almost 
universally  heavier  grades  than  the  main  river.  If 
there  is  a  sudden  expansion  of  the  lava  cap,  and  a  more 
than  ordinary  width  between  the  rims,  such  a  proposi- 
tion is  almost  sure  to  be  found  beneath  the  surface. 
PI.  10,  fig.  2,  represents  such  a  structure  as  would  be 
found  on  the  line  OP  of  pi.  11,  fig.  1,  where  we  have 
two  gravel  banks  c,c,  under  one  lava  cap  a.  Without 
going  into  further  detail  it  may  be  said  that  all  these 
features  can  be  reproduced  in  a  model,  thus  proving 
the  general  accuracy  of  the  theory  of  origin. 

Faulted  Ancient  Channels. — It  is  not  to  be  expected 
in  a  country  which  has  been  the  seat  of  such  compara- 
tively recent  volcanic  activity  that  there  will  be  an 
absence  of  faults  and  dislocations  in  the  channels.  Un- 
fortunately these  are  numerous  and  often  interfere  with 
the  successful  working  of  otherwise  valuable  property. 

Three  examples  of  such  faulting  are  shown  on  pi. 
11,  in  figs.  4,  5  and  6,  all  taken  from  the  mining  re- 
gions of  Plumas  and  Sierra  counties,  Cal.  Fig.  4  shows 
the  situation  at  Grass  Flat,  near  Laporte.  Here  the 
fault  AB  has  cut  the  channel  across  its  general  direc- 
tion, the  left  hand  portion  in  the  figure  having  been 
raised,  or  the  right  hand  portion  depressed,  as  shown. 
The  bedrock  at  e  consequently  acted  as  a  dam,  and 
backed  up  the  water  flowing  down  the  bedrock, 
till  it  formed  an  underground  reservoir  P,  the  drainage 
outlet  of  which  near  A  was  so  near  the  surface  that 
grassy  meadows  were  formed  at  C,  sustained  by  the 
perennial  water  in  P;  hence  the  name.  It  was  impos- 
sible to  work  the  submerged  ground  until  a  long  and 
expensive  drain  tunnel  had  been  run. 


GOLD  GRAVEL  DEPOSITS.  283 

Fig.  5,  same  plate,  shows  a  fault  running  lengthwise 
of  the  channel  in  the  pit  at  Laporte,  ab  being  the  dis- 
location, d  the  bedrock,  c  the  gravel,  and  e  gravel  from 
the  later  series  of  gravels  previously  described,  barren 
and  almost  entirely  devoid  of  quartz  bowlders.  Such 
a  fault  is  not  so  detrimental  to  the  working  of  the  de- 
posit, as  it  can  be  followed  upstream  without  interfer- 
ence; but  in  such  a  case  as  in  fig.  6,  where  the  dikes 
c,c,c,  have  broken  through  and  dislocated  the  gravel 
g,  the  drifting  operations  on  the  bottom  gravels,  shown 
in  black,  became  so  expensive  that  while  the  gravel  was 
rich  the  expense  involved  in  hunting  the  continuation 
of  the  channel  beyond  each  dike  consumed  all  the 
profits. 

Folded  Gravel  Beds. — Instead  of  sharp  faulting, 
gravel  beds  sometimes  show  evidence  of  disturbance 
in  the  shape  of  folds,  either  in  smooth  long  sweeps  or 
in  a  complication  of  smaller  waves  (pi.  12,  figs.  1  and 
2).  Folds  are,  like  faults,  often  accompaniments  of 
volcanic  eruptions,  and  the  gravel  may  be  dragged  with 
the  lava  sheets. 

HILLSIDE  DEPOSITS. — These  have  the  same  origin  as 
those  just  described,  and  are  in  fact  in  many  cases,  if 
not  in  all,  only  their  lower  portions,  which,  being  at 
the  time  of  the  lava  flows  below  the  level  of  the  sea  or 
interior  lakes,  or  for  other  causes,  escaped  the  lava  cap 
which  buried  the  upper  portions  of  the  streams.  As 
the  land  rose  the  streams  began  to  cut  down  into  these 
deposits,  concentrating  the  contained  gold  on  the  bars 
and  riffles  along  their  sides,  which  sustain  a  constant 
renewal  as  the  rainfall  washes  the  hillsides  down  into 
the  river  bottoms. 

There  is  one  class  of  hillside  deposits,  of  local  origin, 
in  which  part  of  the  gold  has,  in  descending,  been  con- 
centrated in  pockets  formed  where  favorable  rock  for- 
mations occur,  as  in  the  case  of  slates  dipping  into  the 
hill.  These  pockets  have  since  been  covered  over  with 
soil  and  debris,  and  some  of  the  gold  may  have  bees 


2S4         PROSPECTING  AND  VALUING  MINES. 

carried  out  of  them  and  further  down  the  hillside, 
spreading  out  in  fanlike  shape.  In  searching  for  such 
pockets  the  prospector  pans  out  samples  of  dirt  along 
the  foot  of  the  hill,  noting  where  pay  or  at  least  some 
gold  begins  and  ends;  then  runs  a  corresponding  line 
of  pan  tests  parallel  and  higher  up,  marking  the  limits 
of  the  pay.  If  this  second  line  is,  as  is  probable, 
shorter,  it  will  indicate  a  triangle  near  the  apex  of 
which  the  pocket  is  sought  for  by  trenching. 

SEA  BEACH  DEPOSITS. • — These  are  mainly  derived 
from  ancient  gravel  beds,  which  are  reconcentrated  by 
being  broken  down  by  the  impact  of  the  waves,  and 
sorted  by  the  waves  and  tides.  As  these  deposits  are 
in  most  cases  the  furthest  removed  from  their  original 
source,  the  contained  gold  is  of  the  very  finest  char- 
acter, and  consequently  the  most  difficult  to  save  by 
mechanical  appliances;  these  difficulties  becoming 
steadily  greater  as  the  size  of  the  particles  of  gold 
diminishes.  If,  however,  the  ocean  were  operating  on 
solid  rocks  of  any  of  the  various  kinds  which  contain 
gold,  there  is  no  reason  why  we  should  not  find  deposits 
of  conglomerate  with  coarse  gold,  gradually  fading  out 
into  finer  and  finer  sediments  with  finer  and  finer  gold, 
as  the  beds  recede  into  deeper  and  deeper  water,  to 
which  only  the  finer  sediments  would  be  carried  by  the 
reflux  of  the  waves,  or  undertow.  And  further,  if  the 
coast  line  which  is  being  destroyed  be  gradually  sink- 
ing, as  we  know  to  be  the  case  in  many  localities,  just 
as  it  is  rising  in  others,  we  should  have  such  a  bed  of 
conglomerates,  consisting  of  the  larger  waterworn  frag- 
ments, extending  over  a  large  area,  both  in  breadth 
and  length,  fading  out  on  its  upper  surface  into  the 
finer  and  poorer  material,  and  in  some  such  way  as 
this  the  beds  of  gold-bearing  conglomerates  may  have 
been  formed.  The  destruction  of  the  shore  line  would 
be  more  rapid  and  the  deposits  more  extensive  than  in 
those  cases  where  the  coast  is  gradually  rising,  as  in 
this  instance  the  same  material  would  be  longer  exposed 


GOLD  GRA  VEL  DEPOSITS.  285 

to  the  abrading  action  of  the  waves,  the  formation  of 
conglomerates  would  be  less,  and  of  fine  sediments 
more  extensive,  and  the  gold  particles  would  suffer 
more  abrasion  and  be  reduced  in  size. 

In  searching  for  gold-bearing  beach  sands,  these  are 
naturally  to  be  looked  for  under  bluffs  of  gravel  and 
conglomerate.  A  favorable  time  is  after  a  strong  wind 
blowing  along  the  coast  line,  which  makes  cross  waves, 
advantageous  for  concentration.  The  best  spots  will 
usually  be  those  marked  by  lines  and  patches  of  black 
sand,  which  are  almost  alwa3rs  concentrated  wherever 
any  gold  is. 

Besides  the  beach  sands  proper,  gold-bearing  sands 
have  been  worked,  off-shore,  by  dredging,  on  the  coast 
of  New  Zealand. 

GLACIAL  DEPOSITS. — Under  this  head  are  included  all 
those  deposits  in  which  ice  has  played  a  part  in  their 
formation,  and  we  have  consequently  evidences  of  more 
complicated  action.  As  in  all  other  deposits  there 
must  be,  to  start  with,  a  belt  of  gold-bearing  rocks  to 
be  removed,  or  the  resulting  mass  will  be  barren. 
Given  such  a  belt  of  rocks  there  is  no  reason  why 
glacial  deposits  should  not  contain  gold,  just  as  those 
which  have  been  derived  from  aerial  erosion,  but  we 
are  likely  to  find  a  greater  variety  in  the  physical  ap- 
pearance of  the  gold,  either  smooth  or  angular,  coarse 
or  fine,  because  it  has  been  released  from  the  contain- 
ing rocks  by  a  variety  of  methods. 

Glaciers  transport  to  the  lower  valleys,  first,  the 
rocks  or  bowlders  which  are  detached  by  frost  from  the 
exposed  bluffs  which  form  their  boundary  walls;  and 
secondly,  the  rounded  bowlders  and  sediment  which 
are  formed  by  their  grinding  action  on  the  rocks  over 
which  they  travel.  If  they  cross  a  belt  of  gold-bearing 
rocks  they  must  discharge  into  the  valleys  the  contents 
of  these  rocks,  along  with  the  remains  of  the  rocks 
themselves,  either  in  the  stream  which  issues  from 
their  "foot,"  or  into  the  terminal  moraine,  if  they 


286         PROSPECTING  AND   VALUING  MINES. 

terminate  on  land;  or  the  contents  may  be  widely  dis- 
persed by  floating  ice  or  icebergs  if  they  terminate  in 
the  water. 

While  morainal  deposits  may  be  unsuited  to  min- 
ing ventures,  the  river  deposits  resulting  from  glacia- 
tion  may  be  worked  by  machinery  suitable  to  the  re- 
tention of  the  excessively  tine  gold,  which  must  neces- 
sarily be  lost  in  the  agitated  waters  of  a  sluice  box. 

GRAVEL    MINING. 

What  Constitutes  a  Workable  Gravel  Proposition. — • 
The  elements  which  go  to  make  a  workable  gravel  mine 
are :  1,  the  amount  of  and  distribution  of  the  gold  in 
the  gravel;  2,  the  width,  continuity,  and  extent  of  the 
deposit;  3,  the  character  of  the  bedrock;  4,  the  depth 
of  the  bedrock  in  relation  to  the  neighboring  ravines; 
5,  the  grade  of  the  channel  or  bedrock  and  freedom 
from  faults;  6,  the  available  dumping  ground  for  the 
waste  material ;  7,  the  character  and  amount  of  the  water 
supply.  While  all  these  elements  enter  into  every 
working  proposition,  they  have  widely  varying  values 
according  to  other  conditions. 

Placer  Mining. — This  term  is  sometimes  used  to  in- 
clude all  methods  of  working  placers  or  gravel  deposits; 
it  is  here  applied  in  the  usual  and  more  restricted  sense, 
excluding  hydraulic  mining  (which  involves  the  use  of 
water  under  pressure)  and  covering  only  those  methods 
of  gravel  washing  (mainl.y  in  recent  placers)  in  which 
the  water  depends  for  its  working  qualities  simply  on 
its  quantity  and  the  grade  of  the  sluice  boxes  in  which 
it  is  used.  The  altitude  of  the  source  of  supply  cuts 
no  figure,  except  as  it  affects  the  grades  on  which  the 
gravel  can  be  washed.  As  this  condition  involves  the 
handling  of  every  pound  of  gravel  by  manual  labor,  or 
practically  so,  it  is  only  the  richer  and  consequently 
the  shallower  deposits  which  are  available,  such  as  the 
beds  of  ravines,  river-bars  and  the  shallower  adjacent 


GOLD  GRAVEL  DEPOSITS.  287 

deposits.  When  the  former  become  too  poor  to  work, 
the  miner  says  he  has  lost  the  channel.  It  is  not 
always  meant  that  there  is  no  longer  indication  of  gold, 
but  its  concentration  is  not  sufficient  to  warrant  hand- 
ling by  such  slow  methods.  For  the  "pan"  and  the 
"rocker"  a  very  small  quantity  of  water  may  be  suffi- 
cient, and  the  amount  of  material  handled  daily  is  so 
comparatively  small  that  the  question  of  dumping 
ground  does  not  trouble  the  miner,  neither  does  the 
grade  of  the  channel,  nor  disturbance  by  faults,  be- 
cause his  appliances  are  movable  on  short  notice;  and 
the  same  may  be  said  of  the  "long  torn"  or  sluice  box 
into  which  the  gravel  is  shoveled  when  working  on  a 
somewhat  larger  scale;  but  the  depth  and  character  of 
the  bedrock  may  be  all  important,  as  it  is  on  the  bed- 
rock that  the  miner  finds  his  chief  reward.  If  he  is 
unable  to  reach  it  on  account  of  the  influx  of  water, 
the  cost  of  wing-damming  the  stream  or  pumping  may 
eat  up  all  the  profits,  and  after  all  the  bedrock  may  be 
such  that  it  has  not  been  able  to  retain  the  gold. 

A  perfectly  smooth  sluice  box  would  permit  all  the 
gold  to  escape,  and  to  avoid  this  the  bottom  is  either 
provided  with  riffles  in  the  shape  of  slats,  or  paved 
with  bowlders  and  sometimes  with  wooden  blocks  cut 
across  the  grain.  All  of  these  methods  provide  crevices 
into  which  the  gold  drops  as  it  is  swept  through  the 
boxes  by  the  force  of  the  wjater,  and  is  thus  prevented 
from  escaping.  The  bedrock  in  a  stream  acts  in  the 
same  way.  If  perfectly  smooth,  as  at  E,  pi.  12,  tig. 
3,  it  may  be  absolute!}7  clean,  there  being  no  obstruction 
to  give  anything  a  retentive  hold.  A  case  of  this 
kind  occurred  at  Gibsonville,  Cal.,  where  a  long 
tunnel  was  run  to  open  a  piece  of  ground  lying  between 
two  mines  which  had  paid  handsomely,  only  to  find  on 
reaching  the  channel  a  perfectly  smooth  bedrock  and 
almost  perfectly  barren.  The  most  favorable  condition 
is  a  bedrock  pitching  down  stream  as  at  A,  in  the  same 
diagram,  so  that  all  the  crevices  are  presented  to  the 


388         PROSPECTING  AND  VALUING  MINES. 

impact  of  the  descending  material.  In  such  crevices 
the  gold  is  literally  jammed  into  the  rock,  and  it  will 
usually  pay  to  mine  from  6  in.  to  1  ft.  of  its  surface 
.ilong  with  the  gravel,  especially  if  it  be  softer,  as  the 
miners  say,  "cheesy."  A  similarly  good  bedrock  is 
formed  by  the  worn  surfaces  of  limestone  B  and  (7, 
which  being  eaten  out  into  irregular  holes  act  as  per- 
fect riffles  and  give  good  results,  as  at  Shaw's  Flat  and 
Columbia,  Cal. ;  but  less  satisfactory  returns  are 
usualb'  had  from  slaty  rocks  pitching  up  stream  as  at 
D,  especially  if  the  rocks  be  hard,  as  objects  slip 
readily  over  such  surfaces.  The  application  of  these 
principles  will  soon  enable  the  prospector  to  work  out 
the  problems  for  himself  and  test  his  theoretical  knowl- 
edge by  experience.  "Potholes,"  which  are  smooth 
round  pits  worn  in  the  solid  rock  by  the  constant  fall 
of  water  charged  with  sand,  or  the  grinding  action  of 
an  imprisoned  bowlder,  like  a  pestle  in  a  mortar,  are 
apt  to  be  swept  clean  of  any  valuable  contents. 
Bowlders  in  the  bed  of  the  stream  of  course  act  as 
riffles,  but  when  large  they  add  materially  to  the  cost 
of  mining,  requiring  derricks  for  their  removal  and 
much  extra  labor.  If  the  gravel  is  cemented,  as  is  not 
infrequently  the  case,  it  may  be  necessary  to  leave  it 
exposed  to  the  air  to  slack,  if  the  cementing  material 
(as  clay)  is  such  as  will  yield  to  such  simple  treat- 
ment; or  it  may  be  even  necessary  to  pass  it  through 
a  stamp  mill;  but  deposits  of  this  character  are  not 
likely  to  attract  the  placer  miner,  as  they  involve  the 
outlay  of  considerable  capital,  which  is  only  warranted 
by  extensive  explorations  and  the  proof  of  extensive 
deposits. 

Gold  Pan. — Prospecting  is  usually  done  with  a  large 
shallow  iron  pan  about  16  in.  or  more  in  diameter 
across  the  top,  by  2|  in.  deep,  with  flaring  sides, 
stamped  out  of  a  single  piece  of  charcoal  sheet  iron, 
called  and  well  known  as  a  "gold  pan."  Such  a  pan 
filled  with  gravel  and  fairly  heaped  in  the  center  will 


GOLD  GRAVEL  DEPOSITS.  289 

hold  about  25  Ib.  and  about  150  pans  are  usually  con- 
sidered equal  to  a  cubic  yard  (the  number  varies  with 
the  size  of  the  pan);  values  of  gravel  being  estimated 
either  by  the  pan  or  by  the  cubic  yard  and  not  by  the 
ton.  A  cent  is  a  piece  of  gold  about  -^  in.  square  and 
half  as  thick  as  a  $5  piece,  as  an  approximation  to  give 
some  comparative  idea  of  size  and  value.  With  these 
figures  the  prospector  can  form  some  idea  of 
what  he  may  be  able  to  do  daily,  as  soon  as  he  has 
found  out  how  many  pans  of  dirt  he  can  wash  daily 
or  how  many  yards  of  gravel  he  can  shovel  into  a 
sluice  box,  both  of  which  will  vary  according  to 
the  locality,  the  character  of  the  ground  and  the  dis- 
tance to  water.  Persistent  panning  is  the  only  thing 
which  will  test  a  gulch.  Just  as  one  swallow  does  not 
make  a  summer,  one  pan  of  good  dirt  does  not  make  a 
mine;  nor  does  the  failure  to  find  gold  in  the  first  pan 
prove  the  locality  to  be  barren.  As  a  usual  thing  an 
abundance  of  quartz  pebbles  in  the  gravel  is  a  good 
indication,  and  when  these  are  accompanied  with  an 
abundance  of  black  sand,  minute  garnets  (transparent 
and  red)  and  small  rounded  shot-like  pebbles  of  chrome 
iron,  it  is  not  well  to  be  easily  discouraged.  The 
signs  of  course  may  fail,  but  they  are  what  the 
Mexicans  term  pintas  or  colors,  and  call  for  a  thorough 
search.  If  the  deposits  are  too  poor  to  be  worked  by 
these  primitive  methods,  but  are  shown  to  carry  gold  (as 
proved  by  extensive  panning)  over  a  large  and  well 
defined  area,  we  may  resort  to  the  methods  employed  in 
Hydraulic  mining,  by  which  we  can  move  and  wash 
per  man  so  vastly  an  increased  quantity  of  gravel,  that 
ground  very  poor  in  its  average  contents  may  prove 
remunerative ;  but  we  must  remember  that  the  hydraulic 
miner  always  calculates  on  a  rich  bottom  streak  which 
has  to  bear  the  loss,  if  any,  involved  in  removing  the 
top  dirt,  which  may  sometimes  be  a  valueless  clay; 
and  generally  stops  work  on  the  bank  when  the  limits 
of  this  bottom  streak  are  reached  laterally 


290        PROSPECTING  AND  VALUING  MINES. 

By  hydraulic  mining  we  understand  the  use  of  water 
under  pressure;  that  is  to  sa3r,  at  some  suitable  point 
the  stream  is  turned  into  pipes  which  convey  it  to  the 
ground  to  be  worked ;  and  by  this  means  we  take  advan- 
tage of  the  weight  of  the  water  in  the  pipes  to  force 
large  quantities  through  a  nozzle,  and  secure  a  power 
to  cut  away  the  gravel  bank  without  the  aid  of  pick 
or  shovel,  and  wash  the  material  into  suitable  sluices. 
According  to  the  pressure  or  head  and  the  amount 
of  water  used,  a  miner's  inch  of  water*  will  wash  from 
3  to-10  cu.  yd.  of  gravel.  The  "head"  is  the  differ- 
ence in  height  between  the  point  at  which  the  water 
enters  the  pipe  and  that  from  which  it  is  discharged; 
while  the  "pressure"  is  equal  to  the  weight  of  a  column 
of  water  of  this  height  multiplied  by  the  cross  sectional 
area  of  the  pipe,  both  in  feet,  by  the  weight  of  1  cu.  ft. 
of  water,  from  which  must  be  deducted  the  loss 
caused  by  friction  (called  the  friction  head)  against 
the  sides  of  the  pipe,  which  will  be  governed  by  its 
length,  size  and  condition  of  its  interior  as  regards 
smoothness  and  cleanliness.  This  loss  is  greatest  in 
small  pipes. 

It  is  evident  that  the  grade  of  the  gravel  to  be 
worked  will  depend  on  the  number  of  yards  which  can 
be  moved  daily  by  a  given  quantity  of  water,  and  that 
this  will  depend  on  the  pressure  under  which  the  water 
is  used.  To  increase  this  pressure  we  have  to  gain 
altitude,  and  this  forces  the  head  of  the  water  supply 
further  and  further  back  into  the  mountains;  and  as 
this  supply  must  be  constant  during  time  of  rain  and 
drought  alike,  we  are  compelled  to  build  reservoirs,  into 
which  the  various  minor  sources  of  supply  are  collected 
and  held  in  reserve.  When  we  remember  that  mines 
such  as  those  at  North  Bloom  field  and  Cherokee  Flat, 
using  2,000  miner's  inches  or  over,  consume  daily 
more  than  33,000,000  gal.,  or  water  sufficient  for  a  city 


*  2,230  cu.  ft.— a  tank  12x12x15  ft.    (See  Chapter  XVII.  on  Water.) 


GOLD  GRA  VEL  DEPOSITS.  291 

of  350,000  inhabitants,  it  is  not  to  be  wondered  at  that 
there  must  sometimes  be  an  expenditure  of  $400,000 
or  $500,000  on  the  water  plant  before  a  yard  of  gravel 
can  be  washed.  With  such  a  heavy  preliminary  ex- 
penditure on  water,  besides  the  cost  of  tunnels, 
sluices,  buildings,  etc.,  at  the  mine,  annual  repairs  and 
working  expenses,  we  must  have  correspondingly 
large  deposits  of  gravel  to  justify  the  enterprise.  The 
North  Bloomfield  Company  in  1879  used  931,000 
miner's  inches  of  water  (15,000,000,000  gal.),  each  inch 
of  which  moved  on  an  average  about  4  cu.  -yds.  of 
gravel,  or  a  total  of  about  3,724,000  cu.  yds.,  equal  to 
2,310  acres  1  ft.  thick,  231  acres  10  ft.  thick  or  23 
acres  100  ft.  thick.  The  actual  area  removed  was  prob- 
ably about  7  acres  some  300  ft.  in  depth.  These  are  of 
course  outside  figures,  but  they  emphasize  very 
strongly  the  necessity  of  a  thorough  inspection  of  the 
water  supply,  and  the  facilities  for  disposing  of  or  im- 
pounding the  debris,  before  opening  an  extensive 
hydraulic  proposition.  It  is  time  enough  to  test  the 
quality  of  the  bank  when  the  water  and  debris  ques- 
tions are  settled. 

It  would  be  beyond  the  proper  scope  and  purpose 
of  the  present  work  to  enter  into  the  details  of  this 
highly  developed  method  of  mining.  For  such  infor- 
mation the  reader  is  referred  to  "A  Practical  Treatise 
on  Hydraulic  Mining  in  California, "  by  Augustus  J. 
Bowie,  Jr.;  "Practical  Notes  on  Hydraulic  Mining," 
by  Geo.  H.  Evans;  "Manual  of  Hydraulic  Mining 
for  the  Use  of  the  Practical  Miner, "  by  Theo.  F.  Van 
Wagenen,  and  other  books  and  current  literature. 

Drift  Mining.- — There  are,  however,  large  bodies  of 
gravel  which  cannot  be  handled  by  purely  hydraulic 
methods  for  one  or  other  of  the  following  reasons:  (1) 
The  water  supply  may  be  totally  inadequate,  or  the 
deposit  may  not  justify  the  expense  of  bringing  it  on 
the  ground;  (2)  the  dumping  ground  also  may  be  in- 
adequate, or  local  interests  may  prevent  it  from  being 


292        PROSPECTING  AND  VALUING  MINES. 

made  available;  (3)  the'  top  dirt  may  be  so  thick  and 
worthless  as  not  to  warrant  its  removal ;  (4)  the  de- 
posit may  be  entirely  capped  with  lava,  which  cannot 
be  economically  removed;  (5)  the  ravines  on  either 
side  of  the  ridge  containing  the  channel  may  not  have 
been  cut  down  deep  enough  to  enable  us  to  put  in  a 
tunnel  on  a  hydraulic  grade,  or  they  may  be  too  flat 
for  suitable  washing  sluices;  or  (6)  the  ravines  may  be 
so  high  that  their  bottom  is  above  that  of  the  old  chan- 
nel, as  in  pi.  10,  fig.  3,  and  we  cannot  gain  access  by  a 
tunnel  under  any  conditions. 

In  this  last  case  it  will  be  necessary  to  work  the  mine 
with  pumping  machinery  through  either  shaft  or  in- 
cline, of  which  latter  method  the  successful  Damascus 
mine  in  California  is  a  good  example;  but  in  this  in- 
stance the  incline  followed  the  channel  on  its  descend- 
ing grade,  and  did  not  involve  the  dead  work  of  shaft- 
ing, the  use  of  which  cannot  be  said  to  have  been  more 
than  partially  successful.  In  all  the  other  cases  bed- 
rock tunnels  are  resorted  to,  which  are  run  through 
the  rim  on  a  water  grade  until  the  channel  is  reached, 
when  the  gravel  is  extracted  and  handled  in  cars  very 
much  in  the  same  way  as  a  coal  mine  is  operated. 
Water  can  be  accumulated  until  sufficient  gravel  is 
taken  from  the  mine,  and  a  clean  up  can  be  made  daily, 
weekly  or  monthly  as  the  case  may  be.  Having  to 
wash  so  small  a  quantity  of  gravel,  comparatively 
speaking,  the  sluice  boxes  may  be  small,  and  but  little 
water  is  required  under  very  slight  pressure  or  none 
at  all,  so  that  the  plant  is  not  necessarily  costly.  Given 
the  gravel,  the  success  of  drift  mining  depends  on  the 
location  of  the  tunnel  with  regard  to  the  bottom  of  the 
channel,  for  many  months  of  labor  and  many  thousands 
of  dollars  may  be  expended  on  a  tunnel  which  may  be 
valueless  if  it  should  unluckily  enter  the  gravel  above 
the  bottom  of  the  channel,  which  it  is  unable  to  drain 
and  render  workable,  as  is  the  case  with  the  lower 
tunnel  in  pi.  11,  fig.  2.  It  is  infinitely  better  to  be 


GOLD  GRAVEL  DEPOSITS.  293 

too  low  than  too  high,  but  the  location  of  these  tunnels 
is  a  problem  which  will  severely  task  the  engineer  and 
geologist  combined. 

The  greater  number  of  the  drift  mines  are  located 
well  up  in  the  mountains,  on  the  steeper  grades  near 
the  head  of  the  old  channels,  and  it  is  only  here  and 
there  that  the  shape  of  the  country  has  caused  the  re- 
moval of  the  lava  cap  and  exposed  the  underlying 
gravel  in  such  a  shape  that  hydraulic  work  was  pos- 
sible, so  that  long  stretches  of  the  ancient  river  lie  be- 
tween these  isolated  spots  where  the  altitude  of  the 
bedrock  has  been  ascertained.  In  these  unexplored 
sections  it  is  only  by  inference  that  we  know  the  chan- 
nel to  exist,  and  numberless  abandoned  tunnels  show 
how  little  the  miners  were  acquainted  with  its  struc- 
ture. To  open  a  mine  in  such  a  situation  is  a  delicate 
task  and  can  only  be  safely  done  after  boring  across 
the  general  line  of  the  old  river,  to  ascertain  the  true 
position  of  its  deepest  portions,  and  its  depth  from  the 
present  surface.  But  before  this  can  be  done  we  must 
determine  the  course  of  the  old  stream  so  that  we  may 
be  sure  that  the  bore  holes  are  located  across,  and  do 
not  follow  it  lengthwise.  To  make  certain  of  this  the 
rim  of  the  channel  on  each  side  of  the  ridge  must  be 
carefully  traced  out  and  platted  as  in  pi.  11,  fig.  1, 
noting  where  the  lava,  pipeclay  or  gravel  shows  in 
contact  with  it;  and  the  survey  should  be  extended  to 
include  the  bed  of  the  ravines  on  each  side  of  the  ridge ; 
levels  should  be  run  the  entire  length  of  the  rim  and 
the  creek  bottoms,  with  full  notes  of  the  rocks  exposed 
in  the  latter,  and  these  levels  will  disclose  the  exposed 
ends  o.f  the  lateral  streams  T,  T,  which  will  outcrop  in 
the  lowest  parts  of  the  rim.  When  such  a  survey  is 
platted  we  can  approximately  draw  in  the  center  line  of 
the  main  channel,  and  of  its  branches,  on  the  plan; 
which  will  cover  only  the  main  stream  where  its  rims 
are  approximately  parallel,  or  the  main  stream  and  a 
lateral  if  there  are  wide  expansions  as  at  OP,  and  an 


294         PROSPECTING  AND   VALUING  MINKS. 

exposure  as  at  /.  From  these  data  we  can  draw  an 
approximate  cross  section  at  any  point,  such  as  pi.  10, 
fig.  4,  in  which  the  rims  are  at  the  same  altitude, 
making  the  unseen  slopes  of  the  old  river  af  and  gf, 
the  same  as  those  visible  between  the  rim  a  and  the  bed 
of  the  creek  h.  It  is  evident  that  under  such  condi- 
tions the  length  of  a  horizontal  tunnel  to  tap  the  bottom 
/would  be  equal  to  the  width  of  the  channel  between 
the  rims  a  g,  as  the  triangles  dca,  abf  and  fbg  are  all 
similar.  More  difficulty  will  attend  the  determination 
of  the  length  on  such  a  line  as  OP,  pi.  11,  fig.  1,  but 
the  solution  is  practicable  as  an  approximation.  Of 
course  this  is  not  an  absolute  method,  as  it  is  based  on 
the  probability  of  the  same  rock  taking  the  same  or 
practically  the  same  slopes  when  worn  away  under 
similar  conditions,  and  this  majr  not  ahvays  be  the 
case;  but  it  will  do  to  determine  whether  a  tunnel  is 
feasible,  as,  if  the  distance  to  the  creek,  as  from  e 
to  h,  is  less  than  one-half  the  width  between  the  rims, 
the  probabilities  are  altogether  in  favor  of  the  condi- 
tions shown  in  pi.  10,  fig.  3.  If  the  rims  are  of  differ- 
ent altitudes,  as  in  fig.  3,  the  center  of  the  old  channel 
will  probably  be  located  proportionately  nearer  the 
lower  rim. 

If  this  preliminary  test  prove  satisfactory  we  can 
locate  the  borings  with  certainty,  and  they  should  be 
not  less  than  three  in  number,  probably  five  or  up- 
wards, as  their  respective  depths  may  indicate.  To 
ascertain  the  probable  grades  of  the  channel  we  must 
extend  our  investigations  to  the  beds  of  the  creeks  on 
each  side  of  the  ridge,  as  it  is  important  to  know  be- 
forehand whether  the  country  is  faulted,  whether  the 
channel  is  choked  by  bowlders,  and  whether  we  are 
likely  to  encounter  flat,  moderate  or  steep  grades  in 
the  ground  when  opened,  as  bad  faulting  might  lead 
to  failure,  and  might  not  be  disclosed  by  the  borings; 
bowlders  are  more  difficult  to  handle  even  than  in  the 
open  air;  and  the  grades,  as  we  have  seen,  largely  in- 


QOLD  GRAVEL  DEPOSITS.  295 

fluence  the  amount  of  gold  in  the  bedrock  gravel. 
There  will  probabbr  be  under  any  circumstances  a  slight 
flattening  at  the  junction  of  each  lateral  branch  with 
the  main  stream.  By  examining  the  modern  ravines 
we  may  possibly  find  in  each  a  band  of  rock  as  F,  pi. 
11,  fig.  1,  which  is  easily  recognizable,  and  by  using 
this  as  a  common  base,  and  following  each  ravine 
both  up  and  down  with  a  line  of  levels,  we  can  arrive  at 
a  very  fair  idea  of  the  probabilities  where  we  cannot 
see  the  bed  of  the  channel  from  what  is  visible  in  those 
of  modern  origin,  especially  if  we  find  the  rock  strata 
occurring  in  orderly  succession  in  each  stream,  on  all 
points  on  which  we  desire  information,  whether  it  be 
faulting,  dip  of  the  rocks,  accumulation  of  bowlders  or 
grade.  It  would  be  possible  to  enlarge  on  this  theme 
almost  indefinitely,  but  enough  has  been  said  to  furnish 
the  key  to  the  methods  of  exploration,  which  must  be 
varied  to  suit  each  particular  locality;  and  the  miner, 
by  the  aid  of  this  key,  can  study  for  himself  the 
chances  of  success.  The  boiing  is  not  difficult  or  ex- 
pensive, and  will  be  nearly  as  satisfactory  as  an  open 
shaft,  which  will  cost  more,  take  more  time  to  sink, 
and  might  not  after  all  be  suitably  located.  The 
trachytic  lavas  seem  to  abound  in  choke-damp  or  car- 
bonic acid  gas,  making  good  ventilation  in  the  shafts 
imperative. 

Machine  Washing. — The  operations  just  spoken  of 
are  based  on  the  use  of  large  quantities  of  water  in 
open  sluice  boxes,  in  which  there  must  inevitably  be  a 
loss  of  fine  gold,  as  the  records  of  the  undercurrents 
show.  Workings  on  a  large  scale  have  demonstrated 
the  presence  in  gravel  of  gold  so  fine  that  it  is  not 
visible  in  the  pan  to  the  naked  eye,  just  as  reasoning 
demonstrated  should  be  the  case  in  gravels  which  owe 
their  origin  to  glacial  action,  or  which  contain  the 
products  of  the  decomposition  of  pyrites.  This  very 
fine  gold  must  certainly  be  swept  away  in  the  swirl  of 
such  streams  as  are  used  in  either  hydraulic  or  drift 


296         PROSPECTING  AND   VALUING  MINES. 

operations,  as  it  takes  a  long  time  to  settle  even  in 
still  water.  To  save  such  gold  it  must  be  brought  into 
contact  with  quicksilver  in  such  a  way  that  it  cannot 
escape  amalgamation.  Such  is  the  intention  of  all 
mechanical  appliances  which  have  been  proposed.  It 
is  sufficient  to  say  that  by  their  means  gold  has  been 
saved  which  is  so  infinitely  fine  that  it  can  be  applied 
as  a  paint  on  paper,  producing  a  gilding  smoother  and 
thinner  than  gold  leaf.  Its  presence  having  been 
demonstrated,  the  apparent  absence  of  gold  in  the  de- 
bris from  localities  where  auriferous  pyrites  have  been 
largely  denuded  is  explained,  and  the  metal  is  probably 
much  more  widely  disseminated  than  has  heretofore 
been  supposed.  The  discovery  of  gold  in  this  condi- 
tion and  the  ability  to  save  it  may  have  far-reaching 
results  in  gold  mining,  especially  as  in  talcose  rocks 
and  serpentines  much  fine  gold  occurs  as  films  of  in- 
finitesimal thinness,  which  increase  the  value  of  the 
assays,  but  is  exceedingly  difficult  to  save  in  the  mill. 
In  a  piece  of  solid  rock  we  have  the  material  con- 
trolled, no  matter  how  fine  it  may  be,  and  can  detect 
its  presence  by  assay  of  even  small  samples,  but  unfor- 
tunately we  have  no  way  of  concentrating  gravel  so  as 
to  get  suitable  assay  samples  except  by  laborious 
processes,  and  may  have  to  depend  on  working  tests 
for  the  detection  of  such  gold. 

Test  for  Fine  Gold  in  Gravel. — Probably  the  best  ex- 
perimental method  would  be  to  wash  a  large  quantity 
of  gravel,  previously  measured,  in  the  same  water, 
never  allowing  any  of  the  latter  to  escape,  but  using 
it  over  and  over  again,  retaining  only  the  finest  sands 
by  a  proper  system  of  screens;  and  when  a  suitable 
quantity  of  sands  had  been  accumulated  they  might  be 
treated  by  the  chlorination  process,  which  dissolves 
every  trace  of  fine  gold  in  the  mass  and  saves 
nearly  all  of  it.  The  result  obtained  divided  by  the 
number  of  yards  of  gravel  concentrated  would  give  the 
average  value  per  yard,  and  this  might  be  greatly 


GOLD  GRAVEL  DEPOSITS.  297 

more  than  shown  by  test  workings  in  the  sluice  box. 
The  difference  between  the  two  results  would  be  the 
invisible  gold. 

All  machines  suitable  for  this  class  of  work  use 
much  less  water  per  yard  of  gravel  washed  than  is 
necessary  in  hydraulic  operations,  and  this  is  a  most 
important  item  if  the  deposits  are  so  situated  that 
pumping  mast  be  resorted  to,  as  a  good  head  of  water 
(pumped)  will  cost  from  15  to  30  cents  per  miner's 
inch  according  to  the  height  to  which  it  must  be 
raised,  and  the  length  of  the  pipe  through  which  it 
has  to  be  forced,  or  the  cost  of  labor  and  fuel. 

Dry  Washing. — The  difficulties  attending  the  sepa- 
ration of  gold  without  the  use  of  water,  or  as  it  is 
called  rather  curiously,  "dry  washing,"  are  enormous, 
and  it  can  only  be  attempted  on  the  richest  kind  of 
material  with  even  a  shadow  of  success.  The  great 
mistake  is  made,  as  in  so  many  other  mining  machines 
and  processes,  originated  by  persons  who  as  a  usual 
thing  are  totally  ignorant  of  what  has  been  attempted 
by  others  before  they  became  inoculated  with  the  idea, 
of  supposing  that  the  careful  manipulation  to  which 
the  inventor  subjects  the  small  quantity  of  material  on 
which  he  operates  can  be  repeated  on  a  large  scale  in 
actual  mining.  For  success  it  is  absolutely  necessary 
that  the  material  should  be  absolutely  dry  and  thor- 
oughly pulverized,  as  any  moisture,  especially  in  clayey 
soils,  will  prevent  the  grains  of  gold  from  separating 
from  the  earthy  matter. 

Hydraulic  Elevators. — -Not  a  few  localities  in  which 
gold  is  found  abundantly  present  difficulties  due  to 
insufficient  room  below  the  deposit,  on  which  we  can 
construct  sluices  of  sufficient  length  to  properly 
wash  the  gravel,  and  in  which  we  can  deposit  the 
debris  after  it  is  washed.  In  such  cases  we  are  com- 
pelled to  resort  to  hydraulic  elevators,  by  which  the 
gravel  is  lifted  from  30  to  50  ft.  or  over  and  there 
dumped  into  the  sluice  boxes,  which  can  then  be  from 


29S          PROSPECTING  AND   VALUING  MINES. 

one-eighth  to  a  quarter  of  a  mile  longer  than  would 
otherwise  be  possible.  The  method  is  of  course  only 
available  on  moderately  coarse  material,  as  the  diame- 
ter of  the  tube  and  the  force  of  the  lifting  jet  prevent 
the  passage  of  very  coarse  material. 

River  Bars. — These  usually  form  at  the  junction  of 
two  streams,  or  just  below  the  point  at  which  the  cur- 
rent is  deflected  from  one  side  of  the  river  to  another. 
If  a  stream  is  auriferous,  these  bars  are  often  rich  in 
gold,  which  is  brought  down  in  flood  time  from  the 
upper  country,  often  many  miles.  The  Snake,  Colum- 
bia and  Fraser  Rivers  are  good  examples  of  such 
streams,  in  addition  to  the  well  known  California 
localities.  On  the  Fraser,  at  Yale,  the  amount  of  fine 
gold  brought  down  by  the  stream,  to  localities  not  less 
than  50  miles  from  the  source  of  supply,  is  so  great 
that  the  surface  of  the  pebbly  bars,  which  act  as  riffles, 
pays  to  work  over  annually;  and  a  panful  of  moss 
gathered  from  the  bowlders  exposed  between  high  and 
lo\v  water  mark,  will  show  from  fifty  to  several  hun- 
dred colors.  It  can  easily  be  understood  from  this 
that  bars  which  have  remained  untouched  for  years 
may  therefore  be  very  rich;  immensely  so  in  some  in- 
stances. Hill's  bar,  below  "Yale,  must  have  yielded 
many  dollars  per  cubic  yard,  when  seven  men  with 
three  rockers  took  out  $90,000  in  90  days.  These  bars 
may  be  so  near  the  level  of  the  water,  that  it  inter- 
feres materially  with  working  them.  In  such  cases 
Wing  dams  are  resorted  to.  These  structures 
consist  of  a  wall  of  brush  and  bowlders,  built  out  in 
the  shallow  water  at  some  suitable  point  above  the 
ground  to  be  worked,  to  divert  the  current  and  inclose 
a  block  of  desirable  ground.  The  current  is  used  to 
run  water  wheels  which  pump  the  inclosure  dry  or 
sufficiently  so  to  enable  the  working  of  the  gravel  to 
be  successfully  carried  on.  Such  structures  are  of 
course  only  available  during  a  low  stage  of  water,  and 
sudden  flood  is  apt  to  wash  them  away,  making 


GOLD  GRA  VEL  DEPOSITS.  299 

the  operation  risky,  as  a  whole  season's  work,  as  well 
as  the  money  invested,  may  be  lost  in  an  hour.  In 
some  few  cases  ifc  may  be  possible  to  divert  the  stream, 
which  is  a  more  satisfactory  method  if  the  ground 
rendered  available  is  sufficiently  extensive  to  justify 
the  expense.  Probably  one  of  the  most  successful 
enterprises  of  this  kind  was  on  the  Cape  claim  near 
Oroville,  in  California,  the  owners  of  which  in  early 
days  turned  the  Feather  River  into  a  flume  40  ft. 
wide,  and  cleaned  up  from  $600,000  to  $700,000  in  one 
summer's  work,  although  they  lost  the  flume  during  a 
sudden  freshet  before  the  job  was  completely  finished. 

Dredging  the  bed  of  the  stream  is  sometimes 
resorted  to,  it  being  reasonable  to  suppose,  from  all  we 
know  of  gravel  mining,  that  if  the  bars  in  a  river  are 
worth  working,  the  gravel  beneath  the  surface,  which 
we  cannot  see,  must  also  contain  gold  in  paying  quan- 
tities. Such  dredges  are  in  successful  operation  in 
several  localities,  both  in  America  and  elsewhere. 
Some  machines  can  handle  as  much  as  150  tons  of 
gravel  an  hour;  but  the  quantity,  as  well  as  the  suc- 
cess of  the  dredge,  will  depend  largely  on  the  character 
of  the  river  bottom.  If  it  is  encumbered  with  large 
bowlders,  it  may  be  impossible  to  work  it  to  advan- 
tage, and  the  best  results  will  be  obtained  in  moder- 
ately fine  material  of  a  uniform  character. 

Adjustment  of  Saving  Appliances  to  the  Size  of  the 
Gold. — In  any  appliance  for  working  gravel  by 
water,  the  measure  of  success  will  largely  depend  on 
the  careful  adjustment  of  the  amount  of  water  used, 
and  the  grade  of  the  tables  or  sluice  boxes,  on  or  in 
which  the  gravel  is  washed,  to  the  size  of  the  particles 
of  gold  in  the  material  under  treatment;  and  the  finer 
and  finer  these  become  the  more  accurate  must  be  the 
adjustment.  There  are  many  localities  where  the  entire 
bulk  of  the  gold  is  so  fine  that  we  have  to  resort  to  the 
use  of  the  principles  involved  in  the  undercurrent,  or 
to  the  use  of  amalgamated  plates,  or  to  a  lining  in  the 


300         PROSPECTING  AND   VALUING  MINES. 

sluice  box,  made  of  inch  boards  bored  full  of  holes,  or 
to  blankets,  burlaps,  or  rawhides  with  the  hair  point- 
ing up  stream,  as  in  China;  or  to  cocoanut  matting 
laid  over  a  coarse  linen  cloth,  as  in  New  Zealand.  The 
localities  where  this  kind  of  gold  is  chiefly  found  are 
along  the  banks  of  large  rivers  and  sea  beaches,  and 
the  gold  is  frequently  accompanied  by  such  large 
quantities  of  "black  sand"  (consisting  of  magnetic 
and  titaniferous  iron  derived  from  the  decay  of  granitic 
rocks)  that  these,  in  any  stream  weak  enough  to  save 
the  flaky  gold,  choke  the  saving  appliances  with  a 
solid  bed  of  iron  sand,  through  which  it  is  impossible 
for  the  gold  to  sink  and  reach  the  riffles  or  quick- 
silvered surface  below,  and  it  is  consequently  passed  on 
through  the  sluices,  on  the  top  of  the  sand.  The  only 
method  of  improving  this  state  of  affairs  is  to  first 
extract  the  iron  sand,  or  that  portion  of  it  which  is 
magnetic,  from  the  material  under  treatment,  so  that 
the  remainder  may  be  finished  in  a  much  gentler  cur- 
rent than  would  be  necessary  to  carry  off  the  iron 
sand,  and  yet  sufficient  for  the  task  of  separating  the 
quartz  sands  from  the  gold.  Various  appliances  have 
been  designed  to  work  these  sands,  but  until  recently 
they  have  met  with  but  a  very  limited  share  of  suc- 
cess. There  appears,  however,  now  to  be  a  prospect, 
by  the  use  of  magneto-electrical  appliances,  of  making 
more  progress  in  the  solution  of  the  problem,  which  is 
a  fascinating  one  on  account  of  the  abundance  and 
widespread  area  of  the  material,  and  its  constant 
restoration  by  the  operations  of  nature. 

In  working  this  class  of  material,  the  aim  should  be 
to  make  the  machinery  as  light  and  portable  as  possi- 
ble, so  that  it  may  be  readily  moved  to  the  material 
instead  of  hauling  the  material  to  the  machine,  as  this 
rapidly  becomes  an  expensive  process,  for  while  the 
material  may  be  abundant  it  is  usually  of  no  great 
thickness  at  any  one  point.  This  is  particularly  the 
case  in  beach  sands,  which  may  be  scattered  by  heavy 


GOLD  GRAVEL  DEPOSITS.  301 

storms  and  afterward  reasserted  by  the  gentler  action 
of  the  waves  in  more  moderate  weather,  which  pan  out 
the  lighter  particles  of  sand,  leaving  the  gold  and  iron 
in  a  concentrated  form. 

Throughout  this  chapter  especial  attention  has  been 
paid  to  gold,  but  the  same  principles  of  prospecting 
and  working  are  equally  applicable  to  all  minerals 
found  in  similar  conditions,  such  as  tin,  platinum  and 
its  allies,  and  even  native  silver  as  at  Planchas  de 
Plata,  in  southern  Arizona.  These  metals  are,  how- 
ever, all  worked  in  open  air  placers,  and  have  not  yet 
been  found,  so  far  as  the  writer  is  aware,  in  paying 
quantities  in  drift  operations,  though  platinum  and 
iridosmine  are  found  in  nearly  all  the  gravel  diggings 
of  California,  along  with  occasional  diamonds. 


CHAPTER  XVII. 
WATER  AND  ITS  MEASUREMENT. 

WATER  plays  so  important  a  part  in  all  mining 
operations  that  the  available  supply  becomes  a  vital 
question,  whether  for  gold  washing,  for  power  or  for 
milling  and  domestic  use.  The  following  simple  rules 
for  ascertaining  the  quantity  and  estimating  the  power 
which  can  be  derived  from  it  will  be  found  useful  in 
this  connection. 

Unit. — Water  may  be  measured  by  the  gallon,  the 
cubic  foot  or  the  miner's  inch,  and  the  use  of  the 
special  term  depends  somewhat  on  the  purpose  to 
which  the  water  is  to  be  applied;  thus,  city  supplies 
are  usually  estimated  in  gallons;  irrigation  quantities 
in  cubic  feet  or  miner's  inches,  and  for  mining  opera- 
tions on  a  large  scale  almost  universally  in  inches. 

Weight. — A  cubic  foot  of  fresh  water,  with  the 
barometer  at  30  in.,  weighs,  at  39°  F.,  62.423  Ib. ; 
62.367  Ib.  at  60°;  62.218  Ib.  at  90°;  and  only  59.7  Ib. 
at  212°,  a  fair  average  being  62.33  Ib.,  but  usually 
called  62.51b.  for  convenience.  Below  39°  the  weight 
decreases,  so  that  at  32°,  or  the  freezing  point,  it  is 
only  57.2  Ib.  and  its  specific  gravity  only  0.9195.  Sea 
water  weighs  from  64.02  to  64.27  Ib.  per  cu.  ft. 

Bulk. — 'A  gallon  of  water  U.  S.  standard  contains 
231  cu.  in.  This  is  equal  to  a  cylinder  7  in.  high  by 
6  in.  in  diameter,  or  to  a  cube  6.1358  in.  on  the  edge, 
and  is 0.13368  of  1  cu.  ft.,  so  that  1  cu.  ft.  contains  7.48 
gal.,  or  in  general  terms  1\  gal. 

Miner's   Inch.  •  —  This  is  the  quantity  of  water  which 


WATER  AND  ITS  MEASUREMENT.  303 

will  flow  through  an  orifice  in  a  1-in.  board,  1  in.  sq., 
in  24  hours.  In  selling  water,  however,  the  water 
companies  sometimes  make  rates  by  the  10-hour  and 
12  hour  in.,  users  not  requiring  it  for  the  full  24  hours. 
The  inch  varies  according  to  the  pressure  under  which 
it  is  discharged.  The  term  arose  in  California  in  the 
early  days  of  gold  mining,  but  the  customs  of  differ- 
ent camps  varied,  as  the  "head/*  by  which  is  meant 
the  distance  from  the  top  of  the  water  to  the  center  of 
the  hole,  ranged  from  4  to  7,  or  sometimes  as  much  as 
8  in.  The  4-in.  head  is  still  used  in  the  irrigation 
districts  of  southern  California,  but  the  6-in.  head  has 
of  late  years  been  considered  the  standard  in  mining 
estimates.  Under  a  4-in.  head,  through  an  orifice  1 
in.  sq.,  the  discharge  is  equal  to  1,728  cu.  ft.  or  12,- 
925  gal.  in  24  hours.  The  6-in.  head  discharges 
about  2,150  cu.  ft.,  or  16,082  gal.  in  the  same  time. 
The  North  Bloornfield  reports,  as  the  results  of  experi- 
ments by  Hamilton  Smith,  give  2,230  cu.  ft.  or  16.680 
gal.  The  measurement  is  made  by  leading  the  water 
into  a  tank,  provided  at  a  height  of  2  in.  from  the  bot- 
tom with  a  horizontal  slot  of  given  dimensions,  say  2 
in.,  which  can  be  closed  by  a  moving  bar,  sliding  in 
it.  If  it  is  desired  to  measure  all  the  water,  this  bar 
is  slid  back  until  it  allows  the  water  to  escape  at  such 
a  rate  that  the  surface  stands  constantly  at  the  re- 
quired head,  and  the  size  of  the  aperture  can  be  read 
off  immediately  by  graduations  on  the  bar.  If  the 
slot  is  2  in.  high  and  the  bar  has  been  slid  back  60  in. 
the  flow  will  equal  2  X  60 •=  120  in.  If  it  is  desired 
to  measure  off  a  definite  quantity  the  slot  or  gate  is 
properly  adjusted,  and  the  waste  gate  opened  until  the 
requisite  head  is  obtained  in  the  measuring  tank. 

Pressure.  —  Water  exerts  the  same  pressure  in  all 
directions.  In  pipes  the  pressure  is  equal  to  the  area 
of  the  pipe  in  feet,  multiplied  by  the  vertical  height 
of  the  pipe  (not  by  its  length),  and  the  quantity  thus 
Ascertained  by  62^  lb,  (the  weight  of  1  cu.  ft.  of 


304 


PROSPECTING  AND  VALUING  MINES. 


•water),  or,  if  the  area  is  calculated  in  inches,  by 
0.432292  of  a  pound  (the  weight  of  a  column  of  water 
1  in.  sq.  and  1  ft.  high),  and  this  by  the  height  ver- 
tically of  the  pipe  in  feet,  the  result  will  be  the  pres- 
sure per  inch  in  pounds.  Moving  water  exerts  less 
pressure  than  when  it  is  stationary,  but  when  cut  off 
suddenly  puts  a  greater  strain  on  the  pipe  than  the 
simple  stationary  load,  to  which  the  momentum  of  the 
moving  column  has  been  added. 

The  following  table  (condensed  from  Trautwine) 
gives  the  weight  of  water,  at  62£  Ib.  per  cu.  ft.,  con- 
tained in  1  ft.  of  pipe  of  different  diameters  from  1  to 
36  in.  The  fractions  of  inches  are  omitted,  as  seldom 
us^d  in  mining  operations. 

WEIGHT  OF  WATER  IN  1  FT.  OF  PIPE. 


Diam. 
in 
Inches. 

Weight, 
Lb. 

Diam. 
in 

Inches. 

Weight, 
Lb. 

Diam. 
in. 

Inches. 

Weight, 
Lb. 

Diam. 
in 
Inches. 

Weight, 
Lb. 

1 

0.33952 

10 

33.952 

19 

122.56 

28 

266.18 

2 

1.3581 

11 

41.082 

20 

135.81 

29 

285.53 

3 

3.0557 

12 

48.891 

21 

149.73 

30 

305.57 

4 

5.4323 

13 

57.379 

22 

164.33 

31 

326.27 

5 

8.4880 

14 

66.545 

23 

179.60 

32 

347.66 

6 

12.223 

15 

76.392 

24 

195.56 

33 

369.74 

7 

16.636 

16 

86.916 

25 

212.20 

34 

392.48 

8 

21.729 

17 

98.121 

26 

229.51 

35 

415.90 

9 

27.501 

18 

110.000 

27 

247.51 

36 

440.00 

The  quantities  increase  as  the  squares  of  the  diame- 
ter of  the  pipes.  Thus  a  36-in.  pipe  contains  four 
times  as  much  as  one  18  in.  in  diameter — 440  to  110. 

Discharge  Under  Head. — The  discharge  of  a  pipe 
from  the  bottom  of  a  reservoir  is  found  by  multiply- 
ing the  area  of  the  orifice  by  the  velocity  of  the 
stream,  which  depends  upon  the  head  or  pressure.  If 
the  opening  is  circular  multiply  the  square  of  the 
diameter  in  feet  or  inches  by  0.7854,  and  this  will  be 
the  area  in  feet  or  inches.  The  velocity  of  discharge  is 
ascertained  by  multiplying  the  square  root  of  the 
bead  in  feet  by  8,03,  and  the  result  will  be  the  veloc- 


WATER  AND  ITS  MEASUREMENT. 


305 


ity  in  feet  per  second.  The  following  table  (con- 
densed from  Trautwine)  gives  the  velocity  of  dis- 
charge in  feet  per  second  for  heads  of  from  50  to  500 
ft.  Intermediate  heads  can  be  made  proportional  to 
the  nearest  figures: 

VELOCITY  OF  DISCHARGE  UNDER  DIFFERENT  HEADS. 


Head. 

Velocity 
Per  Second. 

Head. 

Velocity 
Per  Second. 

50 

56.7 

125 

89.7 

55 

59.5 

150 

98.3 

60 

62.1 

175 

106.0 

65 

64.7 

200 

114.0 

70 

67.1 

225 

120.0 

75 

69.5 

250 

126.0 

80 

71.8 

275 

133.0 

85 

74.0 

300 

139.0 

90 

76.1 

350 

150.0 

95 

78.2 

400 

160.0 

100 

80.3 

500 

179.0 

Power  of  Falling  Water,  (on  the  assumption  that 
one  horse  power  is  equal  to  33,000  Ib.  raised  1  ft.  per 
minute). — Multiply  together  the  number  of  cubic  feet 
of  water  which  fall  per  minute;  the  vertical  height  of 
the  fall  or  head  in  feet;  and  the  number  62.3  (the 
weight  of  1  cu.  ft.  of  water  in  pounds) ;  and  divide  the 
result  by  33,000.  Thus  800  cu.  ft.  of  water  falling  16 
ft.  would  give  a  theoretical  horse  power  of  24.17.  But 
water  wheels  do  not  realize  all  this  power.  Undershot 
wheels  only  realize  from  one-quarter  to  one-third; 
breast  wheels  about  one-half;  overshots,  from  two- 
thirds  to  three-quarters;  turbines  and  wheels  of  the 
Pelton  type  from  three-quarters  to  85%.  In  general 
terms  large  quantities  of  water  under  small  heads  are 
best  utilized  by  turbines;  but  above  20-ft.  heads  the 
impact  wheel  will  be  found  satisfactory  even  up  to 
pressures  of  2,000  ft.  The  makers  of  the  Pelton  wheel 
issue  a  circular  giving  useful  data  in  relation  to  the 
measurement  and  use  of  water,  and  from  it  the  follow- 
ing tables  are  extracted.  The  first  gives  the  b.  p.  of 


306 


PROSPECTING-  AND   VALUING  MINES. 


1  in.  of  water  under  heads  from  1  up  to  1,100  ft. 
This  inch  equals  1|  cu.  ft.  per  minute.  The  table 
assumes  85%  efficiency. 

TABLE  FOR  CALCULATING  HORSE  POWER. 


Heads 
in  Ft. 

Horse 
Power. 

Heads 
in  Ft. 

Horse 
Power. 

Heads 
in  Ft. 

Horse 
Power. 

Heads 
in  Ft. 

Horse 
Power. 

1 

0.0024147 

320 

0.772704 

170 

0.410499 

480 

.159056 

20 

0.0482294 

330 

0.796851 

180 

0.434646 

490 

.183206 

30 

0.072441 

340 

0.820998 

190 

0.458793 

500 

.207-350 

40 

0.096588 

350 

0.845145 

200 

0.482940 

520 

.255644 

50 

0.120735 

360 

0.869292 

210 

0.5071/87 

540 

.303938 

60 

0.144882 

370 

0.893439 

220 

0.531234 

560 

.352232 

70 

C.  169029 

380 

0.917586 

230 

0.555381 

580 

.400526 

80 

0.193176 

390 

0.941733 

240 

0.579528 

600 

.448820 

90 

0.217323 

400 

0.965880 

250 

0.603675 

650 

.569555 

100 

0.24147'0 

410 

0.990027 

260 

0.627822 

700 

.690290 

110 

0.265617 

420 

.014174 

270 

0.651969 

750 

.811025 

120 

0.289764 

430 

.038321 

280 

0.676116 

800 

1.931760 

130 

0.313911 

440 

.062468 

290 

0.700263 

900 

2.173230 

140 

0.338058 

450 

.086615 

300 

0.724410 

1000 

2.414700 

150 

0.362205 

460 

.110762 

310 

0.748557 

1100 

2.656170 

160 

0.386352 

470 

.134909 

Measurement  by  Weirs. — In  general  terms  a  weir 
is  any  obstruction  across  a  stream,  as  a  dam,  over 
which  all  the  water  in  the  stream  is  compelled  to  flow, 
or  so  much  of  it  as  may  be  desired,  which  can  be 
regulated  by  suitable  waste  gates,  which  will  maintain 
a  constant  depth  on  the  weir.  Select  a  place  in  the 
stream,  where  on  being  dammed  a  pond  will  be  formed 
of  sufficient  length  to  check  the  velocity  of  the  stream. 
Across  the  lower  end  of  this  spot  place  a  board  or 
plank,  in  which  a  square  notch  has  been  previously 
cut  through  which  the  water  must  flow.  The  length 
of  the  notch  in  the  dam  should  be  from  two  to  four 
times  its  depth  for  small  quantities  of  water,  and 
longer  for  large  quantities.  The  edges  of  the  notch 
should  be  beveled  toward  the  intake  or  upper  side, 
and  the  clear  fall  below  the  notch  should  be  not  less 
than  twice  the  depth,  that  is  12  in.  if  the  notch  is  6 
in.  deep,  and  so  on,  to  prevent  loss  by  back  water.  In 
the  pond,  from  3  to  6  ft,  above  the  dam,  according  as 


WATER  AND  ITS  MEASUREMENT. 


30? 


the  stream  is  small  or  large,  drive  a  stake,  and  then 
obstruct  the  water  until  it  rises  precisely  to  the  bot- 
tom of  the  notch  (which  must  be  level)  and  mark  the 
stake  at  this  level.  Then  complete  the  dam  so  as  to 
cause  all  the  water  to  flow  through  the  notch,  and 
after  allowing  time  for  the  water  to  settle,  mark  the 
stake  again  for  this  new  level.  If  preferred  the  stake 
can  be  driven  with  its  top  precisely  level  with  the 
bottom  of  the  notch  and  the  depth  of  water  be  measured 
with  a  rule  after  the  water  is  flowing  freely  through 
the  notch,  but  the  marks  are  preferable  in  most  cases. 
The  distance  between  the  marks  is  the  theoretical 
depth  of  flow  corresponding  to  the  depth  in  the  table, 
where  an  example  is  given  of  the  method  of  making 
the  calculation.  The  quantity  thus  obtained  can  be 
converted  into  gallons  or  miner's  inches  as  desired. 

The  following  table  will  save  trouble  in  making  com- 
putations from  weir  measurements : 

TABLE  FOR  WEIR  MEASUREMENT. 

Giving  cubic  feet  of  water  per  minute  that  will  flow  over  a  weir  1  in.  wide 
and  from  y%  to  20%  in.  deep. 


Inches. 

M 

M 

% 

Yz 

% 

H 

% 

0        

.00 
.40 
1.13 
2.07 
3.20 
4.47 
5.87 
7.40 
9.05 
10.80 
12.64 
14.59 
16.62 
18.74 
20.95 
23.23 
25.60 
28.03 
30.54 
33.12 
35,77 

.01 
.47 
1.23 
2.21 
3.35 
4.64 
6.06 
7.60 
9.26 
11.02 
12.88 
14.84 
16.  83 
19.01 
21.23 
23.52 
25.90 
28.34 
30.86 
33.45 
36.11 

.05 
.55 
1.35 
2.34 
3.50 
4.81 
6.25 
7.80 
9.47 
11.25 
13.12 
15.09 
17.15 
19.29 
21.51 
23.82 
26.20 
28.65 
31.18 
33.78 
36.45 

.09 
.64 
1.46 
2.48 
3.66 
4.98 
6.44 
8.01 
9.69 
11.48 
13.36 
15.34 
17.41 
19.56 
21.80 
24.11 
26.50 
28.97 
31.50 
34.11 
36.78 

.14 
.73 

1.58 
2.61 
3.81 
5.15 
6.62 
8.21 
9.91 
11.71 
13.60 
15.59 
17.67 
19.84 
22.08 
24.40 
26.80 
29.28 
31.82 
34.44 
37.12 

.19 
.82 
1.70 
2.76 
3.97 
5.33 
6.82 
8.42 
10.13 
11.94 
13.85 
15.85 
17.94 
20.11 
22.37 
24.70 
27.11 
29.59 
32.15 
34.77 
37.46 

.26 
.92 
1.82 
2.90 
4.14 
5.51 
7.01 
8.63 
10.35 
12.17 
14.09 
16.11 
18.21 
20.39 
22.65 
25.00 
27.42 
29.91 
32.47 
35.10 
37.80 

.32 

1.02 
1.95 
3.05 
4.30 
5.69 
7.21 
8.83 
10.57 
12.41 
14.34 
16.36 
18.47 
20.67 
22.94 
25.30 
27.72 
30.22 
32.80 
35.44 
38.15 

1  

2 

3  

4 

5........ 

6 

7  ,. 

g 

9  

10 

11  
12 

13  

14  .. 

15  

16. 

17  

18  

19  

20  

308         PROSPECTING  AND  VALUING  MINES. 

Suppose  the  weir  to  be  66  in.  long,  and  the  depth  of 
water  on  it  to  be  11|  in.  Follow  down  the  left  hand 
column  of  the  figures  in  the  table  until  you  come  to  11 
in.  Then  run  across  the  table  on  a  line  with  the  11, 
until  under  f  on  top  line  and  you  will  find  15.85. 
This  multiplied  by  66,  the  length  of  weir,  gives 
1046.10,  the  number  of  cubic  feet  of  water  passing 
per  minute. 

Measurement  in  an  Open  Stream  by  Velocity  and 
Cross  Section. — Measure  the  depth  of  the  water  at 
from  6  to  12  points  across  the  stream  at  equal  dis- 
tances between.  Add  all  the  depths  in  feet  together 
and  divide  by  the  number  of  measurements  made; 
this  will  be  the  average  depth  of  the  stream,  which 
multiplied  by  its  width  will  give  its  area  or  cross 
section.  Multiply  this  by  the  velocity  of  the  stream 
in  feet  per  minute,  and  you  will  have  the  cubic  feet 
per  minute  of  the  stream. 

The  velocity  of  the  stream  can  be  found  by  laying 
off  100  ft.  on  the  bank  and  throwing  a  float  into  it  at 
the  middle,  noting  the  time  passing  over  the  100  ft. 
Do  this  a  number  of  times  and  take  the  average. 
Then  dividing  this  distance  by  the  time  gives  the 
velocity  in  feet  per  minute  at  the  surface.  As  the  top 
of  the  stream  flows  faster  than  the  bottom  or  sides — 
the  difference  being  about  8% — it  is  better  to  measure 
a  distance  of  120  ft.  for  float  and  reckon  it  as  100. 

This  method  can  also  be  applied  to  measurements  of 
water  in  flumes.  The  error  will  tend  toward  excess, 
if  the  friction  along  the  sides  and  bottom  is  not 
allowed  for. 


WATER  AND  ITS  MEASUREMENT.  309 

TABLE  FOR  MEASURING  WATER  BY  MINER'S  INCHES. 


Length  of  Opening  in 
Inches. 

Openings  2  Inches  High. 

Openings  4  Inches  High. 

Head  to 
Center 
5  in. 

Head  to 
Center 
6  in. 

Head  to 
Center 
7  in. 

Head  to 
Center 
5  in. 

Head  to 
Center 
6  in. 

Head  to 
Center 
7  in. 

4          .      

Cu.   Ft, 

1.348 
1.355 
1.359 
1  361 

Cu.  Ft. 
1.473 
1.480 
1.484 
1.485 
1.487 
1.488 
1.489 
1.489 
1.490 
1.490 
1.490 
1.490 
1.491 
1.491 
1.492 
1.493 
1.493 
1.493 
1.493 
1.493 
1.494 

Cu.  Ft. 
1.589 
1.596 
1.600 
1.602 
1.604 
1.604 
1.605 
1.606 
1.606 
1.607 
1.607 
1.607 
1.607 
1.608 
1.608 
1.609 
1.609 
1.609 
1.609 
1.610 
1.610 

Cu.  Ft. 
1.320 
1.336 
1.344 
1  349 
1.352 
1.354 
1.356 
1.357 
1.359 
1.359 
1.360 
1.361 
1.361 
1.362 
1.363 
1.364 
1.365 
1.365 
1.366 
1.366 
1.366 

Cu.  Ft. 
1.450 
1.470 
1.481 
1.487 
1.491 
1.494 
1.496 
1.498 
1.499 
1.500 
1.501 
1.502 
1.503 
1.503 
1.505 
1.507 
1.508 
1.508 
1.509 
1.509 
1.509 

Cu.   Ft. 

1.570 
1.595 
.608 
.615 
.620 
.623 
.626 
.628 
1.630 
1.631 
1.632 
1.633 
1.634 
1.635 
1.637 
1.639 
1.640 
1.641 
1.641 
1.641 
1.642 

6  

8                

10    

12  

1.363 
1.364 
1.365 
1.365 
1.365 
1.366 
1.366 
1.366 
1.367 
1.367 
1.367 
1.368 
1.368 
1.368 
1.368 
1.369 
1.369 

14        

16  

18                    

20  

22  

24         

26  

28         

30    

40  

50  

60  

70    

80    

90       

100  .  .  .  .  ,  

CHAPTER  XVIII. 

ARTESIAN   WELLS. 

Definition. — Strictly  speaking,  an  artesian  well 
should  flow  naturally  over  the  top  of  the  pipe  without 
pumping.  The  name  is  very  frequently  but  erro- 
neously applied  to  any  bored  well, but  such  wells  merely 
differ  from  any  ordinary  well  in  the  size  of  the  hole 
and  the  method  of  lining  it. 

Theory. — Artesian  wells  depend  for  their  success  on 
the  property  of  water  finding  its  own  level,  or  the 
tendency  to  stand  at  the  same  height  in  both  the  legs 
of  a  tube  bent  into  the  shape  of  a  U.  We  must  there- 
fore have  for  the  source  of  water  a  region  higher  than 
the  one  where  the  well  is  to  be  sunk,  and  even  then, 
owing  to  the  friction  in  the  ground  and  tube,  the 
water  will  not  rise  quite  to  this  level. 

Basin  Wells. — To  secure  the  best  results  we  must 
have  a  saucer-shaped  basin  of  strata  all  dipping 
toward  the  center,  and  no  part  of  the  rim  of  the  basin 
must  be  lower  than  the  point  at  which  the  well  is  sunk 
(except  as  hereafter  explained);  and  this  basin  must 
be  filled  with  alternating  layers  or  strata  of  material 
which  will  allow  the  ready  flow  of  water,  such  as 
gravel;  and  others,  such  as  clay,  which  will  not  per- 
mit its  passage.  Such  a  condition  of  the  strata  is 
shown  in  pi.  14,  fig.  8.  To  make  it  more  intelligible 
the  vertical  heights  are  made  out  of  proportion  to  the 
horizontal,  but  this  does  not  affect  the  principle. 

We  have  here   three   beds  of  clay,   c,b,d,  and   two 


ARTKSIAN  WELLS.  311 

beds  of  gravel  g  and  e,  with  surface  dirt  a.  Now  if  a 
well  be  sunk  at  the  center  of  the  basin,  as  at  w,  it 
would  penetrate  all  these  beds.  The  upper  bed  of 
clay  c  would  hold  water,  and  if  the  well  did  not  go 
through  it  we  should  have  only  an  ordinary  well. 
But  as  the  stratum  of  clay  c  would  prevent  any  water 
which  fell  on  the  surface  exposure  of  the  gravel  g 
from  reaching  the  surface  again,  this  bed  would  form 
a  reservoir  in  which  the  permanent  water  level  would 
be  the  height  of  its  lower  outlet  If  then  we  extend 
the  well  into  the  gravel  g  we  should  make  a  lower 
opening  and  the  pressure  in  the  underground  reservoir 
would  force  the  water  up  the  well,  and  perhaps  over 
the  top.  But  if  we  extend  the  well  through  g  and  the 
clay  b  into  the  gravel  e  we  shall  have  tapped  a  larger 
reservoir,  the  gravel  being  thicker,  with  a  larger  sur- 
face exposure  at  a  greater  height,  and  the  increased 
pressure  will  cause  the  water  to  rise  above  the  top  of 
the  well,  giving  a  permanent  flow  without  pumping. 
This  is  a  true  artesian  well. 

It  might  however  happen,  as  in  pi.  14,  fig.  9,  that 
a  portion  of  the  strata  had  been  cut  away  and  subse- 
quently overlaid  by  horizontal  deposits  as  at  c,  but  if 
these  should  be  a  retentive  clay,  the  result  would  be 
the  same,  as  the  lower  edges  of  the  gravel  g  lying  be- 
tween the  beds  of  clay  atby  would  be  hermetically 
sealed  by  the  clay  c,  and  the  well  w  would  still  be 
artesian  on  account  of  the  pressure  resulting  from  the 
altitude  of  a  and  b. 

From  the  foregoing  it  will  be  seen  that  the  best 
results  will  be  obtained  in.  those  wells  which  are  near- 
est the  center  of  the  basin.  These  will  be  under 
greater  pressure  than  those  nearer  the  rim  of  the 
basin,  and  the  flow  will  gradually  diminish  as  it  is  ap- 
proached, until  those  nearest  to  it,  penetrating  the 
retaining  clay  higher  than  the  natural  outlet,  will  have 
no  overflow  and  become  pumping  wells.  The  central 
wells  will,  however,  be  more  expensive  to  put  down. 


312        PROSPECTING  AND  VALUING  MINES. 

Exceptional  Cases. — Otber  causes,  however,  than  the 
occurrence  of  saucer-shaped  basins  may  give  rise  to 
favorable  conditions  for  artesian  wells,  as  in  the  case 
of  San  Bernardino  in  Southern  California,  which  lies 
a  few  miles  north  of  Colton.  All  the  wells  in  the 
latter  town  are  supplied  with  windmills,  while  in  San 
Bernardino  there  are  upward  of  800  artesian  wells, 
furnishing  an  immense  flow  of  water.  The  quantity  is 
so  great  that  large  irrigating  ditches  are  supplied 
from  this  source.  The  boundary  line  between  the  two 
regions  is  a  nearly  straight  line  running  west  of  north. 
Along  this  line  there  has  been  an  immense  fault  across 
the  wide  valley  of  the  San  Gabriel  River,  with  its  alter- 
nating beds  of  clay  and  gravel,  which  has  raised  the 
solid  rock  on  the  west,  until  it  acts  as  a  retaining 
dam,  converting  the  valley  to  the  eastward  into  a  huge 
underground  reservoir,  very  much  as  in  pi.  11,  fig.  4, 
where  AB  may  represent  the  fault,  forming  the  reser- 
voir P,  so  that  while  wells  to  the  left  of  A  would  re- 
quire windmills  those  at  C  might  be  artesian.  (The 
illustration  is  drawn  for  a  different  purpose,  but  the 
relative  position  of  the  rocks  and  gravel  beds  is  the 
same.)  Here  the  water  finds  its  way  into  the  up- 
turned edges  of  the  strata,  bounded  by  the  two  walls 
of  the  valley,  and  not  being  able  to  pass  the  barrier  of 
rock  at  the  western  end  of  the  valley  is  forced  to  the 
surface  through  any  opening  piercing  the  retaining 
clays.  That  this  is  the  case  is  proved  by  the  wells 
being  deep  close  up  to  the  break  or  fault  instead  of 
encountering  the  retentive  clays  at  gradually  dimin- 
ishing depths  going  westward. 

Requisite  Conditions. — In  the  case  just  cited,  the  fault 
haviDg  become  impermeable,  or  not  affording  an  out- 
let for  the  water,  an  artesian  basin  was  formed  where 
none  would  otherwise  have  been  possible,  but  it  does 
not  always  follow  that  because  we  have  the  proper 
shaped  basin  it  will  furnish  an  artesian  flow.  If 
the  beds  of  clay  are  thin,  very  slight  earthquake  dis- 


ARTESIAN  WELLS.  313 

turbances  may  have  broken  them,  so  that  they  no 
longer  act  as  retaining  walls,  but  allow  the  escape  of 
the  water  to  other  lower  strata  where  it  may  be  lost; 
or  the  gravel  beds  may  not  be  continuous  over  large 
areas,  but  contained  instead  between  two  layers  of  clay 
united  all  round  like  the  crust  of  a  pie  over  the  fruit, 
in  which  case  there  would  be  no  pressure;  and  some- 
times, when  the  flow  is  small,  a  deeper  sinking  in 
search  of  a  greater  supply  may  allow  the  water  to 
escape  into  a  lower  stratum  having  a  natural  outlet, 
and  the  flow  be  lost  altogether.  So  many  contin- 
gencies surround  the  successful  sinking  of  artesian 
wells  that  only  actual  trial  can  determine  the  proba- 
bility of  success,  except  in  cases  where  obviously 
there  can  be  no. extensive  basin,  as  in  broken  moun- 
tain countries. 

The  writer  sunk  500  ft.  in  the  San  Joaquin  Valley, 
Cal.,  but  never  found  water  which  came  nearer  the 
top  of  the  well  than  12  ft.,  while  further  north,  in 
what  would  have  been  deemed  a  less  favorable  locality, 
18  out  of  19  wells  were  successful  and  the  deepest 
was  less  than  200  ft. 

While  gravel  has  been  spoken  of  as  the  source  of 
water  in  the  foregoing  pages,  it  may  be  found  in  any 
other  porous  rock  which  will  easily  permit  its  flow, 
such  as  sand,  sandstone,  conglomerate,  shale,  chalk  or 
even  limestone,  the  essential  point  being  that  what- 
ever its  nature  it  must  lie  between  two  non-permeable 
strata  of  clay  or  rock.  The  retaining  strata,  instead 
of  clay,  as  assumed  above,  may  be  of  any  compact 
rocks  such  as  hard  and  unbroken  slates,  quartzite, 
etc.  Without  these  there  can  be  no  artesian  well. 
When  such  a  bed  is  found  in  sinking,  the  operator 
may  expect  satisfactory  results,  not  otherwise;  and  if 
water  is  found  beneath  it  in  reasonable  quantity  care 
should  be  taken  not  to  break  the  underlying  one,  for 
the  reasons  already  given. 

If  successful,  artesian  wells  are  invaluable  for  the 


314         PROSPECTING  AND  VALUING  MINES. 

water  supply  of  cities  and  irrigation,  as,  though  in 
some  cases  their  first  cost  may  be  large,  it  is  not  inva- 
riably so,  but  on  the  contrary  often  quite  moderate, 
and  the  annual  repairs  are  nominal. 

Permanence  of  Supply. — The  well  at  Aire  in  Artois, 
France,  has  given  a  stream  rising  11  ft.  above  the  sur- 
face for  the  last  100  years,  but  in  some  cases  where 
the  success  of  the  experiment  has  induced  the  sinking 
of  a  large  number  of  wells  in  the  same  basin,  the  con- 
sequent increase  in  the  size  of  the  outlet,  combined 
with  excessive  demands  on  the  reservoir,  has  dimin- 
ished the  pressure  and  reduced  the  flow,  as  in  the 
London  basin  in  England.  Aside  from  such  causes 
there  is  little  to  fear  except  from  destructive  earth- 
quakes which  may  rupture  the  strata,  but  fortunately 
these  are  rare. 

Examples. — The  following  table  of  a  few  wells  will 
give  some  idea  of  the  depths  which  have  been  attained 
and  show  that  there  is  no  relationship  between  the 
depth  of  the  well  and  the  quantity  of  water  obtained. 
In  "Physical  Data  and  Statistics  of  Calfornia,"  by  W. 
H.  Hall,  there  are  minute  details  of  many  hundreds  of 
wells  varying  in  depth  from  90  to  over  1,000  ft.,  and 
with  bores  ranging  from  2  in.  to  7  in.  As  is  the  case 
elsewhere,  many  of  the  wells  proved  valueless  for 
either  drinking  purposes  or  for  irrigation  on  account 
of  the  large  amount  of  mineral  matter  (chiefb7  the 
salts  of  sea  water)  which  the  water  contains,  the 
amount  running  up  to  as  much  as  231  grains  of  solid 
matter  per  gallon;  but  the  general  results  have  been 
very  satisfactory.  The  deepest  bore  reached  a  depth 
of  2,160  ft.  without  finding  artesian  water. 


ARTESIAN   WELLS. 
SPECIMEN  ARTESIAN  WELLS  AND  BOREHOLES. 


315 


Locality. 

Depth. 
Ft. 

Diameter 
Inches. 

Flow  in 
Gal. 
24  Hours. 

Height. 
Ft. 

Temper- 
ature. 

Grenelle,  France  .'. 
Passy  France     

1798 
1923 

"*28"° 

864,000 
5,582,000 

54 

82° 
82° 

Paris  Basin   France 

300  to  400 

2  8 

London  Basin     

300  to  000 

4 

Chicago 

700  to  1000 

5 

800000 

Sperenberg  Germany 

4194 

13 

Louisville 

2086 

3 

800  000 

76^° 

Bourne    England  

95 

500000 

40 

Philadelphia 

200 

g 

50  000 

California    

72 

4 

271  000 

2 

67° 

California  

85 

3 

139,000 

2 

68° 

California    •  <.  

90 

4 

239  000 

3 

California  

95 

7 

465  000 

68° 

California          .   .         .  . 

100 

3 

224  000 

2V 

California.  .  .  .  <  

106 

6 

315,000 

1 

65Mj° 

California          • 

123 

3 

164000 

2 

California  

123 

7 

1,011,000 

;" 

California                       » 

140 

3 

173  000 

2 

California  

205 

T 

926  000 

California 

300 

r~ 

388000 

7 

64° 

USEFUL  TABLES. 


ELEMENTS  (CLARKE). 


Name. 

Sym- 
bol. 

Atom- 
icity. 

Atomic  Weight. 

Sp.  Gr. 

H=l. 

O=-16. 

Al 

Sb 
(?) 
As 

Ba 
Bi 
B 
Br 
Cd 
Cs 
Ca 

C 

Ce 
Cl 
Cr 
Co 
CborNb 

Cu 

Er 
F 
Gd 
Ga 
Ge 

BeorGl 
Au 
He 

H 
In 
I 

IV. 
V 

(?) 
V 

II 

V 

III 
I 
II 
I 
II 

IV 

III 
I 

VI 
IV 
V 

II 

(?) 

(?) 
(?) 
(?) 

II 

HI 
(?) 
I 
III 
I 

26.91 
119.52 
(?) 
74.44 

136.39 
206.54 
10.86 
79.34 
111.10 
131.89 
39.76 

11.91 

138.30 
35.18 
51.74 
58.55 
93.02 

63.12 

165.06 
18.91 
155.57 
69.38 
71.93 

9.01 
195.74 
(?) 
1.000 
112.99 
125.89 

27.11 
120.43 

(?) 
75.01 

137.43 
208.11 
10.95 
79.95 
111.95 
132.89 
40.07 

12.00 

139.35 
35.45 
52.14 
58.99 
93.73 

63.60 

166.32 
19.06 
156  76 

2.50—2.81 
1    6.62—6.86 
)  5.74  —  5.83  amorphous 
(?) 
)    5.63—5.96 
1    3.70—  4.72  allotropic 
3.75-4 
9.67-10 
2.53—2.68 
2.95-3.19 
7.99-8.69 
1.87-1.89 
1  55    1  80 

AntimonyCstibni1  m) 
Argon        

Arsenic         

Barium    

Bismuth 

Boron       

Cadmium  

Calcium   

f  3.33—  3.55  diamond 
I    1.84—2.5   graphite 
1    1.76-2.10  charcoal 
^  1.72-1.78  lampblack 
6.63-6.73 
1.33  liquefied 
6.20—7.3 
7.72-8.95 
6-7.37 
(    8.39—8.96 
<   8-8.2  allotropic 
(   7.27-8.22  molten 

Cerium   .  .  .  .  . 

Chlorine  

Chromium          .  <  .  . 

Cobalt  

Columbium      (nio- 
bium). 
Copper  (cuprum)  .  . 

Fluorine    

Gadolinium 

Gallium  

69.91 

72.48 

9.08 
197.23 
(?) 
1.008 
113.85 
126.85 

5.93-5.96 
5.469 

1.64-2.01 
19.2—19.47 
(?) 
j    .025-.033  liquefied 

Germanium 

Glucinum    (berylli- 

Gold  (aurum)  
Helium  

Indium  

)    .620—  .628  occluded 
7.11—7.42 
j    4.82-5.02  solid 
1    3.79—4  molten 

Iodine  

USEFUL  TABLES. 

ELEMENTS  (CLARKE).  -  Continued. 


317 


Name. 

Sym- 
bol. 

Atom- 
icity. 

Atomic  Weight. 

Sp.  Gr. 

H=l. 

O=16. 

Iridiuin  

Ir 
Fe 

La 
Pb 

Li 
Mg 
Mn 

Hg 

Mo 
Nd 
Ni 

N 

ds 

0 
Pd 
Ph 

Pt 

K 
Pr 
Rh 
Rb 
Ru 
Sm 
Sc 
Se 
Si 

Ag 

Na 
Sr 
S 
Ta 
Te 
Tr 
Tl 
Th 
Tu 

Sn 

Ti 
W 
U 
V 
Yt 
Y 
Zn 
Zr 

IV 
VI 

in 

IV 

i 
ii 

VI 

II 

VI 

» 

V 
VI 

II 

IV 
V 

IV 

I 
(?)] 

IV 

I 

VI 

(?) 
Ill 

VI 
IV 

I 

I 
II 

VI 
V 
VI 

(?) 
Ill 

IV 

(?) 

IV 

IV 
VI 
VI 
V 

III 
III 
II 

IV 

191.66 
55.60 

137.59 
205.36 

6.97 
24.10 
54.57 

198.49 

95.26 
139.70 
58.24 
13.93 
189.55 
15.88 
105.56 
30.79 

193.41 

38.82 
142.50 
102.23 
84.78 
100.91 
149.13 
43.78 
78.42 
28.18 

107.11 

22.38 
86.95 

31.  as 

181.45 
126.52 
158.80 
202.61 
230.87 
169.40 

118.15 

47.79 
183.43 
237.77 
50.99 
171.88 
88.35 
64.91 
89.72 

193.12 
56.02 

138.64 
206.92 

7.03 

24.28 
54.99 

200.00 

95.99 
140.80 
58.69 
14.04 
190.99 
16.00 
106.36 
31.02 

194.89 

39.11 
143.60 
10H.01 
85.43 
101.68 
150.26 
44.12 
79.02 
28.40 

107.92 

23.05 
87.61 
32.07 
182.84 
127.49 
160.00 
204.15 
232.63 
170  70 

18  61    22  42 

Iron  (ferrum) 

f  7.48-7.87  bar 
1    7.13  reduced  by  C 
\    8.12  electrolytic 
|    6.88  molten 
i.  8.05  molten  steel 
6.05-6.16 
)  11.16—11.50 
}  10.37—10.95  molten 
5.78-  5.89 
1.69-  -2.  24 
6.86—  8.03 
I  14.—  15.19  solid 
1  12.57—13.61  liquid 
8.49—8.64 

Lanthanum  
Lead  (plumbum)  .  .  . 
Lithium  

Magnesium 

Manganese  

Mercury  (hydrar-  1 
gyruin)  .....     f 

Molybdenum 

Neody  mium  
Nickel  

7,81—9.26 
0.37—0.90  liquefied 
21.4—22.477 
0.58—1.24  liquefied 
10.8—12.15 
1.48—2.34 
(  19.5-21.8 
-j  15.79-21.  15  spongy 
J20.98-22.89precip. 
.84—  .87             [black 

Nitrogen      .  . 

Osmium  

Oxygen  

Palladium  

Phos  phorus 

Platinum  

Potassium  (kalium) 
Praseodymium  
Rhodium  

11—12.1 
1.52 
11—12.26 

Rubidium 

Ruthenium  

Scandium  

'"4.2-4.86"" 
2-2.49 
I   9.55—10.62 
J   9.12—  10  molten 
93—  .98 
2.40-2.58 
1.46-2.09 
10.08—10.78 
6.11—6.34 

Silicon                    . 

Silver  (argentum).  . 

Sodium  (natrium).  . 
Strontium 

Sulphur  

Tantalum 

Tellurium  

Thallium.  

11.78-11.91 
10.97—11.23; 

Thorium  

Thulium  . 

Ti  i  (stannum)    .  .  . 

119.05 

48.15 
184.83 
239.59 
51.38 
173.19 
89.02 
65.41 
90.40 

j    7.14—7.60 
|    5.80—  6.02  allotropic 

16.6—19.26 
18.23—18.68 
5.5—5.87 

Titanium  
Tungsten  (wolfram) 
Uranium  , 

Vanadium 

Ytterbium  .   .-  

Yttrium 

Zinc    

6.48—7.21 
4.15 

Zirconium 

318        PROSPECTING  AND  VALUING  MINES. 

The  atomic  weights  here  given  have  been  compiled  by  Prof.  F.  W.  Clarke 
from  the  most  recent  and  reliable  determinations  and  are  adopted  as  stand- 
ard by  the  American  Chemical  Society. 

In  addition  to  the  foregoing  there  are  a  number  of  supposed  elements-- 
actinium, holmium,  idunium,  ilmenium,  mosaadrium,  neptunium,  phillippium 
and  decipium,  not  accepted  as  valid  by  all  chemists.  Argon  and  helium, 
however,  are  placed  in  the  list,  though  little  is  known  about  them. 

The  wide  range  in  specific  gravity  is  due  to  impurity  of  samples  in  some 
cases;  temperature  when  tested;  with  metals  whether  cast,  rolled,  ham- 
mered, etc. ;  and  to  the  fact  that  the  determinations  were  made  by  different 
chemists  using  different  methods. 

In  the  older  chemical  nomenclature  oxygen  v  as  assumed  as  16  to  1  of 
hydrogen.  Later  determinations  give  15.88  to  1.  Consequently  the  values 
of  atomic  weights  are  calculated  on  two  scales,  on  one  of  which  hydrogen  is 
taken  as  1,  and  on  the  other,  oxygen  as  16.  The  differences  are  only 
fractional. 


GENERAL  CLASSIFICATION  OF  MINERALS  (BRUSH). 
I.    MINERALS   WITH  METALLIC   OR   SUB-METALLIC   LUSTER. 

NOTE. — Minerals  having  metallic  luster  are  opaque,  and  do  not  transmit 
light  even  through  their  thinnest  edges.  The  color  of  their  powder,  or  their 
streak,  is  therefore  dark,  though  not  necessarily  black.  The  minerals  with 
sub-metallic  luster  which  are  included  in  this  section  all  give  dark-colored 
streaks.  Many  dark-colored  minerals  whose  luster  is  doultful  have  been 
placed  here,  and  also  in  Section  II. 

A.— FUSIBLE  PROM   1   TO  5     OR  EASILY  VOLATILE. 

1.  Arsenic  Compounds.— B.  B.  on  charcoal  give  a  volatile  coating  of  arsenious 

oxide. 

2.  Selenium  Compounds.— B.  B  on  charcoal  give  a  characteristic  radish-like 

odor  and  impart  an  azure-blue  color  to  the  reducing  flame. 

3.  Tellurium  Compounds.— When  treated  in  a  test-tube  with  5  cc.  of  concen 

trated  H2SO4  and  gently  heated,  the  acid  assumes  a  reddish-violet  color. 

4.  Antimony  Compounds.  — B.  B.  on  charcoal  give  a  dense  white  coating  of 

oxide  of  antimony. 

5.  Sulphides.— When  roasted  in  the  open  tube  or  on  charcoal  give  the  odor 

of  sulphurous  anhydride,  but  do  not  give  the  reactions  of  the  preceding 
divisions. 

6.  Not  belonging  to  the  foregoing  divisions. 

B.— INFUSIBLE,   OR  FUSIBLE  ABOVE  5,   AND  NON-VOLATILE. 

1.  Iron  Compounds.— Become  magnetic  after  heating  B.  B.  in  the  reducing 

flame. 

2.  Manganese  Compounds.— Impart  to  the  borax  bead  in  O,  F.  a  reddish- 

violet  color. 

3.  Not  belonging  to  the  foregoing  divisions. 

II.    MINERALS  WITHOUT  METALLIC  LUSTER. 

NOTE.— Minerals  without  metallic  luster  are  transparent,  although  they 
may  have  such  an  intense  color  that  they  transmit  light  only  through  very 
thin  edges.  The  color  of  their  powder,  or  their  streak  is  generally  white  or 
light-colored,  never  black. 

A.— EASILY  VOLATILE,    OR  COMBUSTIBLE. 

Eapidly  disappear  when  heated  B.  B.  on  charcoal. 


USEFUL  TABLES.  319 

B.— FUSIBLE  FROM  1  TO  5,   AND  NON-VOLATILE,  OR  ONLY  SLOWLY    OR    PARTIALLY 
VOLATILE. 

PART  I.— Give  a  Metallic  Globule   when  fused  with  sodium  carbonate  on 

charco  1. 
J.  Silver  Compounds.— B.  B.  with  sodium   carbonate  on    charcoal   give  a 

globule  of  silver. 
2    Lead  Compounds.— B.  B.  with  sodium  carbonate  on  charcoal  give  a  globule 

of  lead. 

3.  Bismuth  Compounds.— B.  B.  with  sodium  carbonate  on  charcoal  give  a 

globule  of  bismuth. 

4.  Antimony  Compounds.— B.  B.  with  sodium  carbonate  on  charcoal  give  a 

globule  of  antimony. 

5.  Copper  Compounds.— B.  B.  with  sodium  carbonate  on  charcoal  give  a 

globule  of  copper.  The  powdered  mineral  on  charcoal,  after  moistening 
with  hydrochloric  acid,  imparts  an  azure-blue  color  to  the  blowpipe 
flame. 

PART  II.  Iron  Compounds.— Become  magnetic  after  heating  before  the 
blowpipe  in  the  reducing  flame. 

1.  Sulphates,  Arsenides,  and  Phosphates,  chiefly.— Soluble  in  hydrochloric  or 

nitric  acid  without  a  perceptible  residue,  and  without  yielding  gelatinous 
silica  upon  evaporation. 

2.  Silicates. — Soluble  in  hydrochloric  or  nitric  acid,  and  yield  gelatinous  silica 

upon  evaporation,  or  decomposed  with  the  separation  of  silica. 

3.  Not  belonging  to  the  foregoing  divisions.  —Insoluble  in  hydrochloric  acid. 

PART  III.  When  fused  with  sodium  carbonate  on  charcoal  do  not  give  a 
metallic  globule,  and  when  fused  alone  in  the  reducing  flame  do  not 
become  magnetic. 

1.  Salts  of  the  Alkali  and  Alkali-Earth  Metals.— After  intense  ignition  be- 

fore the  blowpipe,  either  in  the  forceps  or  on  charcoal,  the  ignited 
material  giv  s  an  alkaline  reaction  when  placed  on  moistened  turmeric 
paper. 

a)  Easily  and  completely  soluble  in  water. 

b)  L  soluble  in  water,  or  difficultly  or  only  partially  soluble. 

2.  Arsenates.  Phosphates   and    Borates,  chiefly. — Soluble  in   hydrochloric 

acid,  but  do  not  yield  a  jelly  or  a  residue  of  silica  upon  evaporation. 

3.  Silcates.  —Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon 

evaporation. 

a)  In  the  closed  tube  give  water. 

b)  In  the  closed  tube  give  little  or  no  water. 

4.  Silcates. — Decomposed  by  hydrochloric  acid  with  the  separation  of  silica, 

but  without  the  formation  of  a  jelly. 

a)  In  the  closed  tube  give  water. 

b)  In  the  closed  tube  give  little  or  no  water. 

5.  Not  belonging  to  the  foregoing  divisions.    Insoluble  in  hydrochloric  acid. 

C.— INFUSIBLE,    OR  FUSIBLE  ABOVE  5. 

1.  Salts  of  the  Alkali-Earth  Metals.— After  intense  ignition  before  the  blow- 

pipe, either  in  the  forceps  or  on  charcoal,  the  ignited  material  gives  an 
alkaline  reaction  when  placed  on  moistened  turmeric  paper. 

2.  Carbonates.   Sulphates,  Oxides,  Hydroxides   and  Phosphates,  chiefly. — 

Soluble  in  hydrochloric  acid,  but  do  not  yield  a  jelly  or  residue  of  silica 
upon  evaporation. 

3.  Silicates.  —Soluble  in  hydrochloric  acid,  and  yield  gelatinous  silica  upon 

evaporation. 

4.  Silicates.— Decomposed  by  hydrochloric  acid  with  the  separation  of  silica, 

but  without  the  formation  of  a  jelly., 


320         PROSPECTING  AND  VALUING  MINES. 

5.  Not  belonging  to  the  foregoing  divisions.    Insoluble  in  hydrochloric  acid. 

a)  Hardness  less  than  that  of  glass  or  a  good  quality  of  steel.     Can 

be  scratched  by  a  knife. 

b)  Hardness  equal  to  or  greater  than  that  of  glass.    Cannot  be 

scratched  by  a  knife. 


CHARACTERS  OF  MINERALS  (DANA). 

1.  Name,  synonyms. 

2.  Crystalline,  form  and  structure. 

System  of  crystallization. 

Axial  ratio  and  angular  elements. 

Twinning 

General  structure,  amorphous  varieties,  initiative  forms,  etc. 

3.  Physical  characters : 

Cohesion,  Cleavage,  Fracture,  Hardness. 

4.  Characters  relating  to 

Heat, 

Electricity, 

Magnetism. 

5.  Taste  and  odor. 

6.  Chemical  composition. 

7.  Pyrognostic  qualities  (blowpipe). 


SYSTEMS  OF  CRYSTALLIZATION  (DANA). 

I.  Isometric— 3  equal  axes,  at  right  angles  to  each  other.    (Ex. — cube,  octa- 

hedron ,  dodecahed  ron = py rite). 

II.  Tetragonal — 3  axes.    The  2  lateral  axes  equal,  the  vertical  axis  longer  or 

shorter:  all  at  right  angles  to  each  other. 

III.  Hexagonal  and  Rhombohedral,  4  axes;  3  lateral  axes  in  same  plane  at 

60°  from  each  other  and  a  fourth  vertical  axis  at  right  angles  to  them 
and  either  longer  or  shorter. 

In  the  Hexagonal  system  proper  there  are  4  principal  planes  of 
symmetry;  3  equal  planes  intersecting  at  60°,  and  a  fourth  unequal, 
normal  to  them ;  also  3  auxiliary  planes  diagonal  to  the  first  set  (ex- 
ample, apatiie  group). 

The  Rhpmboheclral  system  includes  forms  with  only  3  planes  of 
symmetry  intersecting  at  12u°  in  the  vertical  axis.  (Ex.  rhombohe- 
dron—  many  forms  of  calcite  and  tourmaline). 

IV.  Orthorhombic— 3  unequal  axes  at  right  angles  to  each  othe-;  3  planes 

of  symmetry,  which  intersect  in  these  axes  but  are  all  different. 

V.  Monoclinic— 3  unequal  axes,  of  which  one  lateral  axis  is  inclined  to  the 

vertical  axis,  the  other  angles  right  angles;  1  plane  of  symmetry. 

VI.  Triclinic— 3  unequal  axes,  and  their  intersections  are  all  oblique. 


MINERAL  CHARACTERS  DEPENDING  UPON  'LIGHT  (DANA). 
Kinds  of  Luster : 

1.  Metallic;  sub-metallic. 

2.  Adamantine  (like  diamond). 

3.  Vitreous  (like  broken  glass). 

4.  Resinous  (like  yellow  resinj. 

5.  Greasy  (like  elaeolite). 

6.  Pearly. 

7.  Silky  (the  result  of  a  fibrous  structure). 


USEFUL  TABLES.  321 


Degrees  of  Intensity : 

1.  Splendent. 

2.  Shining. 

3.  Glistening. 

4.  Glimmering. 


INDIVIDUALIZATION    OF  CRYSTALS  (CROSBY). 

I.  Distinct,  separate  and  so  nearly  perfect  minerals  that  their  proper  forms 

may  be  clearly  recognized^  crystallized. 

II.  Confused  mass  showing  crystal  faces  or  planes  and  cleavage  planes. 

but  no  perfect  crystals  (rock  salt  and  white  marble)— crystalline  or 
massive. 

III.  Crystalline  form  and  cleavage  both  entirely  wanting  to  the  unaided 

eye,  but  the  specimen  shows  double  refraction  when  a  thin  section  is 
viewed  by  polarized  light  (chalcedony)=cryptocrystalline  or  com- 
pact. 

IV.  Entirely  devoid  of  crystallization  (opal  and  obsidian)— amorphous. 
Implanted  crystals =crystals  of  uniform  size  thickly  set  on  a  surface. 
Drusy=very  small  implanted  crystals. 

INTERNAL  STRUCTURE  OF  MINERALS  (CROSBY). 

Granular— Fine  to  coarse = in  grains. 

Compact  or  impalpable=when  the  grains  are  invisible  to  the  naked  eye. 

Glassy  or  vitreous=no  trace  of  granular  structure  even  under  microscope; 

may  be  crystalline  (like  vitreous  quartz)  or  amorphous  (like  obsidian). 
Lammellar= lamination  independent  of  crystallization,  or  dependent.   In  the 

first  case  called  b  ;nded;  in  the  second,  foliated. 
Fibrous=if  coarse,  called  columnar  or  baaded. 


EXTERNAL  FORMS  OF  MINERALS  (CROSBY). 

Botryoidal=rounded,  grapelike. 

Mammillary= larger  rounded  prominences. 

Stalactitic= deposited  from  solution  by  dripping  water  from  overhanging 
rock. 

Stalagmitic^Deposited  from  solution  by  dripping  water  on  floor  of  caves,  etc. 

Tufaceous— porous  deposits  formed  when  reeds,  grasses,  moss,  etc.,  are  in- 
crusted  by  mineral  solutions. 

Concretionary = rounded  mass  or  nodule  produced  by  aggregations  of  min- 
eral matter  in  the  body  of  a  rock. 

Pisolitic— if  the  concretions  are  small  (about  size  of  peas). 

Oolitic = if  very  small  (fish  roe  or  mustard  seed). 

Geodes=hollow  concretions. 

Amydaloids — almond  shaped,  deposited  in  the  vesicles  or  steamholes  of  lava 

Dendritic,  arborescent,  mossy = (stains  of  iron  and  manganese,  native  copper, 
etc.),  resembling  vegetation. 

Reticulated. = net-like. 

Plumose — feather-like. 

Filiform— wire  or  thread-like. 

Acicular=like  needles. 


FRACTURE  (CROSBY). 
Conchoidal = shelly. 
Even. 
Uneven. 

Earthy  (like  clay  or  chalk). 
Hackly. 
Splintery. 


322        PROSPECTING  AND  VALUING  MINES. 

SCALE  OF  FUSIBILITY  OF  MINERALS  (VON  KOBELL). 

1.  Stibnite  (antimony  glance),  large  fragments  are  fusible  in  the  ordinary 

flame  of  a  candle. 

2.  Natrolite;  fine  needles  are  fusible  in  the  flame  of  a  candle;  large  frag- 

ments fuse  to  a  globule  B.B. 

3.  Almandite  (alumina-iron  garnet);  infusible  in  the  flame  of  a  candle;  can  be 

fused  to  a  globule  B.B.  if  in  small  fragments. 

4.  Actinolite  (var.  amphibolite):  fusible  to  a  globule  in  fine  splinters  B.B. 

5.  Orthoclase:  in  very  fine  splinters  is  still  fusible  to  an  irregular  globule;  if 

in  larger  fragments  only  the  edges  are  rounded  B.  B. 

6.  Bronzite  (diallage);  only  the  finest  edges  or  points  can  be  rounded  B.B. 

To  these  Crosby  adds  : 

7.  Quartz;  infusible  alone,  B.B. 


THE  GEOLOGIC  SERIES,  ACCORDING  TO  LE  CONTE. 


Eras. 

Ages. 

Periods. 

Epochs. 

5.  Psychozoic  .  . 

7.    Age  of  Man. 

Human.  23. 

Recent. 

4.    Cenozoic... 

6  .    Age  of  Mamm  als  .  . 

f  Quaternary  22 

(  Terrace. 
<  Cham  plain. 
(  Glacial. 
(  Pliocene. 
<  Miocene. 
(  Eocene. 

j 
[.Tertiary  21 

3.    Mesozoic  .  .  . 

5.  Age  of  Reptiles  — 

(  Cretaceous  ...          20 

-<  Jurassic  19 
(  Triassic  18 

Upper. 
2.  Palaeozoic... 

Lower. 

CARBONIFEROUS 

4.    Age    of  Acrogens 
and  Amphibians. 

(  Permian  17 

-\  Carboniferous  16 
(  Sub-carboniferous.  15 

DEVONIAN. 

3.    Age  of  Fishes  

(  Chemung    .         .  .  14 

J  Hamilton  13 

1  Corniferous  12 
LOriskany  11 

SILURIAN. 

2.  Age  of  Invertebrates 

CAMBRIAN. 

f  Helderberg  .  .      .10 

Salina  9 

Niagara  .                    8 

Trenton  7 

[  Canadian                   6 

(  DikelocephaPs  zone  5 
<  Paradoxides  zone.  .  4 
f  Olenellus  zone  3 

1  .    Archaean  or 
Archaezoic  

1    Archaean 

\  Huronian  2 

/  Laurentian  1 

USEFUL  TABLES* 


323 


THE  GEOLOGIC  SERIES,  ACCORDING  TO  DANA. 
[See  also  p.  68  for  the  system  adopted  by  the  U.  S.  Geological  Survey.] 


Age  of  Man,  or  Quaternary. 

Mammalian  Age. 

Tertiary  Period. 

Reptilian  Age. 

Cretaceous. 

Jurassic. 

Wealden  (epoch). 

Oolitic  (epoch). 

Liassic  (epoch). 

Triassic. 

Carboniferous  Age. 

Permian. 

Carboniferous. 

Sub-carboniferous. 

Devonian  Age, 
or  Age  of  Fishes. 

Catskill. 

Chemung. 

Hamilton. 

Corniferous. 

Silurian  Age,  or 
Age  of  Inverte- 
brates. 

Upper  Siluria-i. 

Oriskany. 

Lower  Helderberg. 

Salina. 

Niagara. 

Lower  Silurian. 

Trenton. 

Canadian. 

Primordial,  or  Cambrian. 

Below  the  Lower  Silurian  come  the  azoic  schists  and  granite. 


324 


PROSPECTING  AND   VALUING  MINES. 


CLASSIFICATION  OF  ROCKS. 
A.  Igneous  Rocks.    B.  Aqueous  and 
IGNEOUS 


Glassy. 

Acid  Glasses. 
Obsidian,    Perlite,    Pumice, 
Pitchstone. 

Chief  Feldspar  Orthoclsae. 

Chief  Feldspar 

Biotite  (or)  (and)  Hornblende 
(or)  (and)  Auglite. 

Biotite  (or)  (and) 
Hornblende. 

+Quartz. 

—Quartz. 

Nepheline 
or  Leucite. 

+Quartz. 

—Quartz. 

TRACHYTE  GROUP. 

ANDESITE  GROUP. 

Felsitic 
and 

Rhyolite. 

Trachyte. 

Phonolite 
(rare). 

Dacite. 

Andesite. 

Porphyritic. 

(Quartz 
Porphyry.) 

(Prophyry.) 

Leucite 
Phonolite 
(very  rare). 

(Porphy- 
rite.) 

(Porphy- 
rite.) 

(Quartz 
Felsite.) 

(Felsite.) 

Fragmental. 

Rhyolite 
Tuff  and 
Breccia. 

Trachyte 
Tuff  and 
Breccia. 

Phonolite 
Tuff  and 
Breccia. 

Andesitic  Tuff 
and  Breccia. 

GRANITE  GROUP. 

DIORITE    GROUP. 

Granitoid. 

Granite 
(Pegmatite) 

Syenite 
(rare). 

Nepheline- 
Syenite 
(rare). 

Leucite- 
Syenite 
(very  rare). 

guartz- 
iorite 
(Tonalite). 

Diorite. 

Si03. 

80.65# 

65.55# 

60.50# 

70.60# 

65.05$ 

USEFUL  TABLES. 


325 


ACCORDING  TO  PROF,  J.  F.  KEMP. 
^Eolian  Rocks.    C.  Metamorphic  Rocks. 
ROCKS). 


Andesite  Obsidian. 


Basic  Glasses, 

Scorias,  Tachylite, 

Basic  Obsidian. 


Plagioclase. 

Nepheline, 
Leucite. 

No  Feldspar. 

Pyroxenes. 

A  Series  of 
Rare  Basaltic 
Rocks. 

Augite  (or)  (and) 
Hornblende 
(or)  (and)  Biotite. 

~  Olivine. 

+Olivine. 

—  Olivine. 

-fOlivine. 

Augite- 
Andesite. 


Oli  vine- 
free 
Basalt. 


(Diabase.) 


Basalt. 


Dolerite. 


(Oli  vine- 
Diabase.) 


With  Nephel- 
ine, Leucite 
(  eldom  Meilite) 
one  or  all. 


Not  readily 

distinguishable 

from  Basalt 

without  the 

microscope. 

Extremely  rare 

in  America. 


Augitite. 


Limburgite 


Not  readily  distinguish 
able  from  Bas  lit. 

Extremely 
rare  in  America. 


Basaltic  Tuffs  and  Breccias. 


GABBRO                     GROUP. 

Diabase. 
Gabbro. 

Anortho- 
site. 

Olivine- 
Diabase. 

Olivine- 
Gabbro. 

Theralite 
(extremely 
rare). 

Pyroxen- 
ite. 

Peridotite. 

Ice. 

Norite. 

Olivine- 
Norite. 

55.45$ 

45.38# 

55.40:* 

45.300J< 

30.00# 

Ultra-basic 
Rocks. 


Basic 
Segrega- 
tions 
in  normal 
Magmas. 

Meteorites. 
Water. 


326         PROSPECTING  AND   VALUING  MINES. 

THE  PRINCIPAL 


Grand 
Divisions. 

Origin. 

Structure. 

Material. 

Incoherent 
State. 

Sand. 

Gravel. 

Shingle.  I 
Rubble,  f 

Arenaceous 
or  sandy. 

Volcanic  frag- 
ments. 

Volcanic  ash. 

Stratified. 

Aqueous 
and  .^Eolian 
(the  latter 
only  slightly 
stratified, 
of  fine 
mated  Is 
usually  not 
compacted). 

More  or 
less  earthy. 

Argillaceous 
or  clayey. 

Mud. 
Clay. 

Calcareous  or 
limey. 

Ooze. 
Chalk. 
Chemical  pre- 
cipitate. 

Metamorphic 
or 
Transition. 

Aq'.eous, 
with  subse- 
quent heat, 
pressure   and 
chemical 
agencies. 

Roughly 
stratified;  in 
part  crystal- 
line; usually 
fissile. 

USEFUL  TABLES. 


ROCKS  (LE  CONTE). 


Compacted  State. 

Essential  Components. 

Remarks. 

Sandstoi.e. 

Silica,  often  with  iron  oxide. 

Grit. 

Small  pebbles  (mostly  quartz)  ce- 
mented with  silica  and  iron  oxide. 

Conglomerate. 

Large  pebbles  and  bowlders 
similarly  cemented. 

Breccia. 

Angular  fragments  (usually  volcanic) 
of  various  rocks,  cemented  with 
silica  and  iron  oxide. 

Tufa. 

Fine  volcanic  dust  compacted  under 
water. 

Shale, 

Indurated  particles  of  clay,  usually 
with  some  quartz  grains  and 
iron  oxide. 

Limestone. 

Calcite,  amorphous  or  partly  crys- 
talline. 

Magnesian    lime-  iy 
stone,  dolomite,  f 

Dolomite  and  calcite. 

Magnesite. 

Magnesite. 

Gneiss. 

Mica,  quartz,  feldspar. 

Mica  schist. 

Mica,  quartz,  feldspar. 

Chlorite  schist. 

Chlorite,  quartz,  feldspar. 

Talcose    schist. 

Talc,  quartz,  feldspar. 

Hornblende  schist. 

Hornblende,  quartz,  feldspar. 

Garnet  schist. 

Garnet,  quartz,  feldspar. 

Slate. 

Hardened  shale,  cleavage  across 
stratification  planes. 

Quartzite. 

Altered  sandstone. 

Marble. 

Altered  limestone,  calcite. 

Serpentine. 

Altered  magnesian  minerals. 

328         PROSPECTING  AND  VALUING  MINES. 

THE  PRINCIPAL 


Grand 
Divisions. 

Origin. 

Structure. 

Material. 

Occurrence. 

Occurring 
massive. 

Unstratifled. 

Igneous. 

Crystalline. 

Plutonic  or 
massive. 

Occurring  in 
intrusions. 

Volcanic  or 
true  eruptives. 

Occurring  in 
overflows. 

Besides  the  essential  components  there  are  many  minor  u  accidental  " 
rphic— such  as  magnetite,  pyrite,  olivine,  etc.,  but  these  usually  occur  in 


USEFUL  TABLES. 
ROCKS  (LE  CONTE).—  (Continued.) 


329 


Compacted  State. 

Essential  Components. 

Remarks. 

ACIDIC— 

Pegmatite  (graphic 

Large  plates  of  mica  imbedded  in 

granite). 

feldspar. 

Granite. 

Quartz,  orthoclase  feldspar,  mica. 

Eurite  or  granulite. 
Syenite. 
Quartz  syenite. 

A  fine-grained  granite. 
Orthoclase  feldspar,  hornblende. 
Quartz,  orthoclase  feldspar,  horn- 

Entirely crystalline 
(holocrystalline)  ; 

blende. 

usually  coarse 

Porphyritic  granite 

Large  crystals  of  feldspar  in  a 
finer  groundmass. 

grained 
(microcrystalline). 

BASIC-r 

Diorite. 

Plagioclase  feldspar,  hornblende. 

Quartz  diorite. 

Plagioclase  feldspar,  hornblende, 

quartz. 

Gabbro. 

Plagioclase  feldspar,  augite,  <  livine 

(granitoid  variety  of  diabase). 

ACIDIC— 

Quartz  porphyry. 

Microcrystalline  groundmass,  with 

Felsite. 

larger  crysta's  of 
orthoclase  and  quartz. 
Microcrystals  of  orthoclase  and 

Microcrystalline 
groundmass,  with 
or  without 

BASIC— 

Diorite. 

quartz. 
Piagioclase  and  hornblende  (micro- 

larger  crystals 
imueaaeci. 

crystalline). 

Diabase. 

Augite  and  hornblende  (microcrys- 

talline). 

ACIDIC— 

Glassy      ground- 

Rhyalite. 

Vitreous  groundmass.  with  crystals 

mass,  with  fine  to 

of  quartz  an    orthoclase 

coarse  crystals  im- 

(sanidin). 

bedded,  or  wholly 

Trachyte. 

Vitreous  groundmass,  with  crystals 

vitreous.     Usually 

of  orthoclase  (sanidin). 

fine-grained  (micro- 

Phonolite. 
Light  colored 

Vitreous  groundmass,  with  crystals 
of  sanidin  and  nepheline. 

crystalline)  or  im- 
oerfectly     crystal- 

scoriae. 
Pumice. 

ine  (cryptocrystal- 
ine).  The  following 

Obsidian. 

exist  in  the  stony 

BASIC— 

condition  ;  rhyolite, 

Andesite. 

Vitreous  groundmass,  with  crystals 

iparite,     trachyte, 

of  plagioclase,  augite  or  hornblende. 

Dhonolite,      basalt, 

dolerite  and  ande- 

Basalt. 

Vitreous  groundmass,  with  crystals 
of  plagioclase,  augite  and  olivine. 

site.   The  following 
are  glassy:  Scoriae, 

Black  scoriae. 
Tachylite. 

pumice,     obsidian, 
and  tachylite. 

or  accessory  minerals  in  most   rocks,  especially  in  the  igneous  and  meta- 
small  proportions. 


330         PROSPECTING  AND   VALUING  MINES. 

CLEAVAGE  (CROSBY) 
Kinds : 

In  the  isometric  (I.)  system I  Cubic,  octahedral  dodeca- 

—tetragonal  (II.)  system f     hedral,  etc. 

— hexagonal  and  rhombrohedral  (III.)  system! 

— orthorhombic  (IV.)  system.  )  \  prismatic,  basal  and 

— monoclinic  (V.)  system .....  >•  pinacoidal . . . .  /          pyramidaL 

— triclinic  (VI.)  system . . . . ...  )  J 

Degrees  : 

Perfect  or  eminent  (like  mica). 

Distinct. 

Indistinct  or  imperfect 

In  traces. 

Difficult. 


MINERALS   DISTINGUISHED    ACCORDING  TO  TOUCH  OR 
FEEL  (CROSBY). 

Meager  (like  chalk,  clay,  etc).         Smooth. 
Harsh.  Unctuous. 

Rough.  Greasy. 


MINERALS  DISTINGUISHED  ACCORDING  TO  TASTE  (CROSBY), 

Astringent.  Saline. 

Cooling.  Alkaline. 

Sour.  Adhesive. 
Bitter. 


MINERALS   DISTINGUISHED  ACCORDING  TO  ODOR  (CROSBY). 

Sulphurous.  Argillaceous  (like  clay) 

Arsenical  (like  garlic).  Fetid  (like  some  limestones). 

Horseradish  (selenium). 


SCALE  OF  HARDNESS  (MOHS). 

1.  Talc  (foliated),  very  soft. 

2.  Gypsum  (compact  alabaster),  can  be  scratched  by  the  finger  nail. 

3.  Calcite,  can  be  crushed  between  the  teeth. 

4.  Fluorite,  easily  scratched  by  knife  steel. 

5.  Apatite,  about  the  hardness  of  knife  steel. 

6.  Feldspar  (orthoclase),  easily  scratched  by  quartz. 

7.  Quartz  (crystalline),  scratches  ordinary  glass. 

8.  Topaz,  easily  scratches  quartz, 

9.  Corundum,  scratched  only  by  diamond. 
10.  Diamond,  the  hardest  mineral  known. 

Dr.  F.  M.  Endlich  says :  "  In  testing  the  hardness  of  a  mineral  by  this 
scale,  care  should  be  taken  that  the  pure  mineral,  not  a  mixture,  is  obtained. 
If  a  mineral  scratches  calcit  ,  but  is  scratched  by  fluorite,  to  about  the  same 
degree,  its  hardness  lies  nearly  midway  between  3  and  4,  and  is  expressed  by 
3.5.  If  it  barely  scratches  calcite,  but  is  decidedly  scratched  by  fluorite,  the 
hardness  is  3—3.5;  if  nearer  to  fluorite  in  hardness,  but  still  scratched  by 
it,  the  hardness  is  8.5-4." 


USEFUL  TABLES. 


VALUES  OF  METAI^,  ORES,  MINERALS,  ETC. 


331 


[Quotations  are  those  ruling  in  the  United  States  January  1,   1899.    The 
selling  point,  when  not  otherwise  stated,  is  assumed  to  be  New  York  City.] 


Substance. 

Unit. 

Price. 

Remarks. 

NON-METALLIC. 
Abrasives: 
Corundum  .  .  .  <,  

Lb. 

Long  ton. 
Long  ton. 
Short  ton. 
Short  ton. 
Lb. 
Short  ton. 
Lb. 
Lb. 
Short  ton. 
100  Ib. 
100  Ib. 
Short  ton. 

Short  ton. 

Short  ton. 
Short  ton. 

Long  ton. 
Lb. 
Short  ton. 
Lb. 
Lb. 

Bbl. 
Bbl. 
Bbl. 
Short  ton, 
Long  ton. 

Short  ton. 

Short  ton. 
Long  ton. 
Short  ton. 
Short  ton. 
Short  ton. 
Short  ton. 
Short  ton. 
Lb. 
100  Ibs. 
Lb. 
Lb. 
Short  ton. 
Short  ton. 
Short  ton. 
IOC  Ib. 

4.5-lOc. 

$20.  00-40.  00 
18.50-32.00 
38.00-57.00 
10.50 
4-40c. 
$3.00 
6-18c. 
17-30c. 
$12.00 
1.65 
1.25-1.75 
19.50 
f  40.00 
!    18.00 
j    30.00 
I  40.00-60.00 
12.12 
j     7.75 
1    10.00 
3.00-4.50 
3^-5c. 

$&E 

6%  7^C. 

Best  ground 
Crude  Naxos. 

Lump. 
Lump. 
Lump. 

Lump. 

Best  Cuban. 
Lower  grade. 
Trinidad. 
Utah  gilsonite. 

Crude. 
Best. 

Crystal  and  Powder 

Barrels  of  300  Ibs. 
Barrels  of  400  Ibs. 
Barrels  of  350  Ibs. 
Commercial  lump. 

J  Domestic  f.  o.  b  at 
1     works. 
Best 
Scranton,  Pa. 
Pittsburg. 

Denver. 
Pittsburg. 
Denver. 

Best  grade. 
From  Greenland. 
Ground. 
Lump. 
Crushed. 
Lump. 

Diatomaceous  or  in- 
fusorial earth  ..... 

Emery  

Rottenstono  

Tripoli  

Aluminum  sulphate..  .  . 
Asbestos  •  • 

Asphaltic  limestone.  .  .  . 
Barytes  

Bauxite         

Bituminous  sandstone  . 
Borax        

Bromine 

45c. 

65c.75 
$1.75@,2.50 
1.65 
2.00-2.10 

$20.25 

7.50-9.50 

4.00-5.00 
2.00 
40-70c. 
$2.95 
1.25 
1.84 
1.25 
$1.76-1.85 
57^c.65c 
3%c.  4c 
8^c. 
$7.00-7.75. 
2.50-4.00 
6.00 
75c.85c 

Cement,     natural    hy- 
draulic                  .... 

Cement,  Portland  

Cement  slag            .  .  . 

Chalk                 

Chrome  ore 

day    china  

Clay  fire 

Coal,  anthracite,  stove 
Coal  bituminous 

Coal  cannel  

Coal  lignite 

Coke,  Connellsville  .... 
Coke,  Trinidad  
Cobalt,  oxide  

Copperas 

Copper  sulphate  
Cryolite        .             .... 

Feldspar 

Flint  silica      

Fluorspar 

Fuller's  earth  

332         PROSPECTING  AND  VALUING  MINES. 

VALUES  OF  METALS,  ORES,  MINERALS,  'ETC.- Continued. 


Substance. 

Unit. 

Price. 

Remarks. 

Grahamite        

Short  ton. 
Lb. 
Long  ton. 
100  Ib. 
Long  ton. 

Long  ton. 

Long  ton. 

Bbl. 

Short  ton. 
Short  ton. 
Long  ton. 
Short  ton. 
Lb. 

$33.00 
lM-4^c. 
$4.00 
2.55 
3.25-3.65 

2.10-3.25    j 

J     3.25-3.65 
i     2.55-3.25 
75c.-$1.00 
$91.50 
7.00-8.00 
2.05 
8.00 
4-6c. 
1 

Ceylon,  crude. 
Rock. 
Crude. 
Cleveland,  bessemer. 
Cleveland,    non-bes- 
semer. 
Cleveland  bessemer. 
"    Non-bessemer. 
Barrels  of  250  Ibs. 

Crude  lump. 

501 

According     to    size 
and  quality. 
Slag.  H 
92#. 
Imported. 
American. 
American. 
American  lead. 
Chinese  quicksilver. 
English  quicksilver. 
American,  dry. 
American,  extra  dry. 
Bbl.  of  42  gal.,  crude. 

American  lump  ore, 
Barrels  of  280  Ibs. 
Crude. 

"  Square  "  =  100  sq. 
ft.  as  laid  on  roof. 

Lump,  Sicilian. 
Southern. 
New  York. 

98& 

9o#; 

Sheets. 
Nickel  alloy. 
Cookson's. 
Other. 
Lake. 
Pittsburg. 

At  furnace. 

Graphite  (plumbago).. 
Gypsum             .           .  . 

iron  ore,  hematite  
Iron  ore  limonite.  .  •  • 

Iron  ore,  magnetite.  .  .  . 

Litharge  

Manganese  ore            .  . 

Marble  flour  ,  .  .  . 

Mica  ground            .... 

100  Ib. 
Short  ton. 
Lb. 
Short  ton. 
Lb. 

Lb. 

Lb. 
Lb. 
Bbl. 
P.  unit. 
Gal. 
Long  ton. 
Bbl. 
Lb. 
Short  ton. 

Square. 

Short  ton. 
100  Ib. 
Lb. 
Long  ton. 
Short  ton. 
Short  ton. 
Lb. 

Lb. 

Lb. 

Lb. 
Long  ton. 
Troy  oz. 
Long  ton. 

$1.00-4.00 
140.00 
6-8c. 
$8.00-15.00 
5M-6c. 
(        14-1  6c. 
4        90c. 
(        90c. 
4V4-6C. 

^°- 

7-10c. 
Be. 

$3.25-5.00 
3.50-6.00 
3-3%c. 

$4.00-6.00 

2.  25-10.  50  -j 

11.00 
1.50-1.60 
13-1  4c. 

$19.00-21.50 
10  00  15  50 

Monazite  

Paints    ocher    

Paints  red  led 

Paints  vermilion  

Paints  white  lead   .... 

Paints  zinc  white    .... 

Phosphate  rock  

Pitch  coal  tar  

Pyrites                  • 

Salt  ground  

Saltpeter  

Slate  ground  

Soapstone               

Sodium  nitrate  
Strontium  carb.  prec  . 
Sulphur  

Talc  common  

Talc,  fibrous  

8.00-9.00 
2.00-3.00 

(        30-34c. 
30-43C. 
1         38c. 
[        33-39c. 
J        9i4c. 
1       8-M-8%c. 
12%c. 
$50.00 
20.67 
11.25  11.50 

Uranium  oxide  

METALS. 

Copper    

Ferromanganese  
Sold    

Iron,  No  2  foundry.  .  .  . 

USEFUL  TABLES.  333 

VALUES  OF  METALS,  ORES,  MINERALS,  ETC.— Continued. 


Substance. 

Unit. 

Price. 

Remarks. 

Iridium  

Gram 

$1.19 

Price  in  Germany 

Lead.               •     ... 

100  Ibs 

3  75 

New  York 

Nickel  

Lb 

33  36c 

Accord'sr  to  Quantity 

Platinum.                   . 

Troy  oz 

$14  50  16  00 

Quicksilver  

Flask 

41  00 

New  York;   flask  of 

Silver....  

Troy  oz 

59^3  60c 

76^  Ibs. 
Com''!  valu© 

Spiegeleisen    

Long  ton 

$23  00 

Zinc  

100  Ib 

5  00 

New  York 

RARE  ELEMENTS. 
[Prices   given     are    ai 
makers'  works  in  Ger 
many,   unless    other 
wise  noted.] 
Barium  —  Amalgam  — 
Electrol  

Gram. 
Gram. 

$1.19 
5.71 

Beryllium  —  Powder  
Crystals  '.  .  . 

Gram. 
Gram. 

5.95 
9.04 

Nitrate 

Oz 

2  50 

New  York 

Boron- 
Amorphous,  pure  — 
Crystals,  pure  
Nitrate 

Gram. 
Gram. 
Lb 

19c. 
:    $1.43 
1  50 

New  York 

Calcium—  Elect'  ol  
Cerium    Fused 

Lb. 
Gram 

4.28 
2  02 

Nitrate  

Lb 

28  00 

New  York 

Chromium  —  Fused  
Pure  powder  

Kg. 
Kg. 

5.95 
1  79 

Chem.  pure  cryst  
Cobalt  —  (98@99$) 

Gram. 

Ke- 

19c. 

$5  35  5  71 

Pure  

if: 

30  94 

Didymium  —  Powder.  .  . 

Nitrate 

Gram. 
Oz 

3.81 
4  00 

New  York 

Erbium  

Gram 

3  09 

Nitrate  

Oz. 

3.00 

New  York 

Gallium.       

Grain 

9  52 

Germanium—  Powder.  . 
Fused     

Gram, 
Gram 

33.32 
35  70 

Glucinum—  Powder  
Crystals  ... 

Gram. 
Gram 

5.95 
9  04 

Nitrate  ,  

Lb. 

2.50 

New  York 

Indium            .  .   . 

Gram. 

4  05 

Lanthanum  —  Powder... 
Electrol,  in  balls  

Gram. 
Gram. 
Oz 

4.28 
9.04 
3.50 

New  York 

Lithium  

Gram 

2  38 

Nitrate  
Molybdenum  —  Po  *vder 
Fused,  electrol  
Niobium        

Oz, 

Kg. 
100  grams. 
Gram 

60c. 
$2.62 
15.47 
3  81 

New  York. 

Osmium 

Gram 

95c 

Palladium—  Sponge  — 
Sheet  and  wire  

Gram. 
Gram.    . 

95c. 

$1.70 

334        PROSPECTING  AND  VALUING  MINES. 

VALUES  OF  METALS,  ORES,  MINERALS,  ETC.— Continued. 


Substance. 

Unit. 

Price. 

Remarks. 

Rhodium 

Gram 

$2  87 

Rubidium—  Pure  
Ruthenium  —  Pure  
Selenium—  Com!  pwd'r 
Sublimed  powder.  .  .  . 
Sticks     

Gram. 
Gram. 
Kg. 
Kg. 
Kg 

4.76 
1.55 
26.18 
35.70 

28  56 

Silicium  —Amorphous.. 
Crystals  pure 

100  grams. 
100  grams 

2.87 
7.14 

Strontium—  Electrol..  .  . 
Tantalum    Pure 

Gram. 
Gram 

6.19 
3  57 

Tellurium    C.  p.  sticks 
Powder  

100  grams. 
100  grams. 

11.90 
9.52 

Thallium 

23  80 

Thorium- 
Nitrate,  45@-50$  

Gram. 
Lb. 

7.85 
7.50-8.00 

New  York, 

Titanium  

Gram. 

71c. 

Uranium  

Gram. 

48c. 

Nitrate          

Oz 

25c. 

New  York, 

Vanadium—  Fused  ..... 
Wolfram    Fused 

Gram. 
100  grams 

$1.19 
23.80 

Powder,  95@98£  
Chem  pure              .  . 

If: 

2.38 
7.14 

Ore  

IS 

47.60 

Lump. 

Yttrium                          . 

Gram 

3.33 

Nitrate  

Oz. 

4.00 

New  York. 

Zirconium    Com1!     .  .  • 

Ks 

119  00 

Pure  

Gram. 

71c. 

Nitrate 

Oz 

$1.00 

New  York. 

USEFUL  TABLES. 


335 


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336        PROSPECTING  AND   VALUING  MINES. 


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USEFUL  TABLES.  337 

The  only  material  standard  of  customary  length  authorized  by  the  U.  S. 
Government  is  the  Troughton  scale,  whose  length  at  59°. 02  Fahr.  conforms  to 
the  British  standard.  The  yard  in  use  in  the  United  States  is  therefore  equal 
to  the  British  yard. 

The  only  authorized  material  standard  of  customary  weight  is  the  Troy 
pound  of  the  Mint.  It  is  of  brass  of  unknown  density,  and  therefore  not 
suitable  for  a  standard  of  mass.  It  was  derived  from  the  British  standard 
Troy  pound  of  1758  by  direct  comparison.  The  British  avoirdupois  pound 
was  also  derived  from  the  latter,  and  contains  7000  grains  Troy. 

The  grain  Troy  is  therefore  the  same  as  the  grain  avoirdupois,  and  the 
pound  avoirdupois  in  use  in  the  United  States  is  equal  to  the  British  pound 
avoirdupois. 

The  British  gallon  =  4.54846  liters. 

The  British  bushel  =  36.3477  liters. 

By  the  concurrent  action  of  the  principal  Governments  of  the  world  an 
International  Bureau  of  Weights  and  Measures  has  been  established  near 
Paris.  Under  the  direction  of  the  International  Committee,  two  ingots  were 
cast  of  pure  platinum-iridium  in  i  lie  proportion  of  9  parts  of  the  former  to  1 
of  the  latter  metal.  From  one  of  these  a  certain  number  of  kilograms  were 
prepared,  from  the  other  a  definite  number  of  meter  bars.  These  standards 
of  weight  and  length  were  mtercompared,  without  preference,  and  certain 
ones  were  selected  as  International  prototype  standards.  The  others  were 
distributed  by  lot  to  the  different  Governments  and  are  called  Natio  al  pro- 
totype standards. 

The  metric  system  was  legalized  in  the  United  States  in  1866. 

The  International  Standard  Meter  is  derived  from  Metre  des  Archives,  and 
its  length  is  defined  by  the  distance  between  two  lines  at  0°  Centigrade,  on  a 
platinum-iridium  bar  deposited  at  the  International  Bureau  of  Weights  and 
Measures. 

The  International  Standard  Kilogram  is  a  mass  of  platinum  iridium  depos- 
ited at  the  same  place,  and  its  weight  in  vacuo  is  the  same  as  that  of  the 
Kilogramme  des  Archives. 

The  liter  is  equal  to  a  cubic  decimeter  of  water,  and  it  is  measured  by  the 
quantity  of  distilled  water  which,  at  its  maximum  density,  will  counterpoise 
the  standard  kilogram  in  a  vacuum,  the  volume  of  such  a  quantity  of  water 
being,  as  nearly  as  has  been  ascertained,  equal  to  a  cubic  decimeter. 
Long  ton:  2240  Ib.  avoirdupois    =1016       kilogram. 
Short  ton:  2000  "  "  =907.2 

Pound  avoirdupois  —  453.6     grams. 

Flask  of  mercury =76)^  Ib.  avoir.  =    34.700  kilogram. 
Troy  ounce  =    31. 104  grams. 

Gallon  rr      3. 785  liters. 

Barrel  of  petroleum  =    42        gal.  =    1.59  hectoliter, 

"       "  salt  =  280        Ib.        127        kilogram. 

41       "  lime  =  200         "•  90.720 

"      "  natural  cement  =300         "         136.080        " 

"       "  Portland  cement  =  400         "         181.440        " 

Gold  coining  value  per  oz.  Troy  =  $20.6718      =  $0.6646  per  gram. 
Silver     "  "      "     "   Troy  =  $1.2929      =$0.04157"      " 


GOOD    BOOKS    OF  REFERENCE. 

[Any  of  the  following  books  can  be  obtained  at    list  prices,    carriage 
prepaid,  from    the  Scientific    Publishing  Co.,  253  Broadway,  New  York, 


ASSAYING. 

Assayer's  Guide.    By  O.  M.  Liebeiv , 1.50 

Assayer's  Manual.    By  Bruno  Kerl ....  3.00 

Assaying.    By  C.  H.  Aaron,  Part  I.^Gold  arid  Silver  Ores $1.00 

Parts  II.  arid  III.,  Gold  and  Silver  Bullion,  Lead,  Copper,   Tin, 

Mercury 1 .75 

Assaying,  A  Text-Book  on.  By  C.  &  J.  J.  Beringer , 3.25 

Assaying,  Manual  of  Practical.    By  John  Mitchell 10.00 

Assaying,  Notes  on.     By  P.  de  P.  Ricketts  and  H.  Miller 3.00 

Assaying  of  Lead,  Copper,  Silver,  Gold  and  Mercury.     By  T.  Bodeman  1.50 

Assaying  With  the  Blowpipe,  Quantitative.   By  E.  L.  Fletcher 1.50 

Practical  Metallurgy  and  Assaying.    By  A.  H.  Trliorns 1.50 

Manual  of  Practical  Assaying.     By  II .  Van  F.  Furman 3.00 

Manual  of  Assaying.    By  W.  L.  Brown 2  50 

and  B.  Kerl ., . . .  „  i.50 

CHEMISTRY. 

Alkali  Maker's  Pocket  Book,    By  G.  Lunge 3.0G 

Alkali  Manufacture  in  Great  Britain,  in  Vol.  II.  of  "  The  Mineral  In- 
dustry " ...... 5.00 

Alum  and  Sulpha:e  of  Alumina.  By  John  Enequist,  in  Vol.  III.  of  "  The 

Mineral  Industry  " -5.00 

Briefer  Course  in  Chemistry.    By  Ira  Remsen 1.12 

Chemical  Analysis.    By  D.  O'Brine 2.00 

Chemical  Analysis  of  Iron.     By  A.  A.  Blair 4.00 

Chemical  Analysis,  Select  Methods  in.  By  Wm.  Crookes 8.00 

Chemical  and  Metallurgical  Handbook.    By  J.  H.   Cremer  and  G.  A. 

Bicknell 2.75 

Chemical  Technology.    By  C.  E.  Groves  and  W.  Thorpe 7.50 

Chemical  Technology.    By  R.  Von  Wagner.. . , 7.50 

Chemistry  for  Engineers  and  Manufacturers.  By  B.  Blount  and  G. 
Bloxam.  Vol.  L,  Chemistry  and  Engineering,  Building  and  Metal- 
lurgy   3..50 

Chemistry,  Principles  of.    By  D.  Mendeleeff 10.00 

Dictionary  of  Applied  Chemistry.    By  T.  E.  Thorpe.    Vol.  I.  (A-I)y), 

$15.00;  Vol.  II.  (Eau-Nux),  $15.00;  Vol.  III.  (O-Z),  $20.00;  complete. . .  50.00 

Electro-Chemical  Analysis.    By  E.  F.  Smith 1.25 

Electro- Chemistry  and  Electro-Metallurgy.    By  W.  Borchers.    In  Vol. 

IV.  of  "  The  Mineral  Industry  " 5.00 

Electro-Chemistry.    By  G.  Gore 80 

Electro-Chemistry.    By  M  ,x  Le  Blanc 1.50 

Electrolysis.    By  H.  Fontaine 3.50 

Engineering  Chemistry.    By  T.  B.  Stillman ,V.  4.50 

Industrial  Chemistry.    By  J.  Payen 10.50 

Inorganic  Chemistry  for  Beginners.    By  H.  E.  Roscoe  and  J.  Lunt .  .75 

Laboratory  Manual  and  Principles  of  Chemistry.   By  G.  M.  Richardson.  1.10 

Laboratory  Manual.    By  Ira  Remsen 40 


GOOD  BOOKS  OF  REFERENCE.  339 

Metallurgical  Analysis.    By  N.  W.  Lord. , . .  1.25 

Potassium  Cyanide  Manufacture,     By  Titus  Ulke.    In  Vol.  IV.  of  ''The 

Mineral  Industry  " , „ 5.00 

Qualitative  Analysis,  Notes  on.    By  W.  P.  Mason 80 

Qualitative  Chemical  Analysis,  A  Short  Course  in.     B.  C.  A.  Schaeffer.  1.50 

Qualitative  Chemical  Analysis.    By  F.  Clowes. 2.50 

Qualitative  Chemical  Analysis.    By  C.  R.  Fresenius , 5.00 

Qualitative  Chemical  Analysis.    By  A.  A.  Noyes ,  1.25 

Qualitative  Chemical  Analysis.    By  John  A.  Miller 1.50 

Quantitative  Analysis.    By  H.  C.  Bolton 1.50 

Quantitative  Chemical  Analysis.   By  T.  E.  Thorpe 1.50 

Quantitative  Chemical  Analysis  by  Electrolysis.     By  A.  Classen 3.00 

Quantitative  Chemical  Analysis.    By  H.  P.  Talbot 1.50 

Quantitative  Chemical  A  alysis.     By  C.  R  Fresenius... 6.00 

Salts,  Tables  and  Quantitative  Analysis.   By  M.  M.  Pattison  Muir.   = . . .  .50 

Sulphuric  Acid  Manufacture.     By  Geo.  Lunge,  3  vols 35.00 

Volumetric  Analysis.    By  H.  W.  Shimpf 2.50 

Volumetric  Analysis.    By  F.  Sutton 4.50 

ELECTRICITY. 

Electric  Transmission  of  Energy.    By  G.  Kapp, 3.50 

Electric  Transmission  Handbook.  By  F.  B.  Badt. 1.00 

Electrical  Distribution.    By  M  H.  Kilgour,  H.  Swan  and  B.  H.  W.  Boggs  4.00 

Electrical  Engineering.     By  W.  Slingo  and  A.  Brooker 3.50 

Electrical  Engineering  as  a  Profession.    By  A.  I).  Southam 1.25 

Electrical  Pocket-Book.     By  G.  Munro  and  A.  Jamieson 2.50 

Electrical  Power  Transmission.    By  L.  Bell 2.50 

Electrical  Transmission  of  Energy.     By  A.  V.  Abbott 4.50 

Electricity  and  Water  Power.    By  M.  A.  Replogle 1 .00 

Electricity  for  Engineers.    By  C.  Desmond „ . .  2.50 

Electricity  in  Mining.    By  S.  P.  Thompson 80 

EXPLOSIVES  AND  BLASTING. 

Blasting.    By  O.  Guttmann 3.75 

Blasting  and  Quarrying.    By  J.  Burgoyne , 60 

Blasting  in  Mines,  Quarries,  Tunnels,  etc.   By  A.  W.  and  Z.  W.  Daw. . . .  6.00 

Explosives  and  Their  Powers.     By  M.  Eerthelot 9.75 

Explosives  and    Explosive  Compounds,  A  Brief  Primer  of.    By    M. 

Berthelot 50 

Lectures  on  Explosives.    By  W.  Walke 4.00 

Modern  High  Explosives.    By  M.  Eissler 4.00 

Nitro- Explosives.    By  P.  G.  Sanford 3.00 

Rock  Blasting.    By  G.  G.  Andre 3.0C 

GEOLOGY. 

Aspects  of  the  Earth.    By  N.  S.  Sha;er. 2.5C 

Chemical  and  Geological  Essays.     By  T.  S.  Hunt 2.50 

Economic  Geology.    By  R.  S.  Tarr 4.00 

Elementary  Geology.    By  R.  S.  Tarr 1.40 

Elements  of  Geology.    By  J.  LeConte 4.00 

Engineering  Geology.    By  W.  H.  Penning 1 .40 

Field  Geology.    By  W.  H.  Penning 1.40 

Field  Geology,  Outlines  of.    By  A.  Geikie 1.00 

Genesis  of  Ore  Deposits.    By  F.  Posepny 2.50 

Geological  Story  Briefly  Told.    By  J.  D.  Dana 1.15 

Geology.     By  A.  J.  J.  Brown 1.00 

Geology.    By  J.  Prestwich.    Vol.  I.  Chemical  and  Physical 6.25 

Vol  II.  Stratigraphical  and  Physical 9.00 

Geology,  Class  Book  of.    By  A.  Geikie 1.10 

Geology,  Comparative.    Translated  by  P.  Lake 4.50 

Geology,  Compend  of.    By  J.  LeConte 1.20 

Geology,  New  Text-Book  of.    By  J.  D.  Dana 2.00 

Geology  of  Colorado  and  Western  Ore  Deposits.    By  G.  Lake 2.50 


340        PROSPECTING  AND   VALUING  MINES. 

Geology,  Practical  Aids  in.  By  G.  A.  J.  Cole 3.00 

Geology,  Principles  of.  By  Sir  John  Lyell 8.00 

Geology,  Text-Book  of.  By  A.  Geikie 7.50 

Hand-Book  of  Rocks.  By  J.  F,  Kemp 1.50 

Limestones  and  Marbles.  By  S.  M.  Burnham 6.00 

Lithology.  Manual  of.  By  E.  H.  Williams 3.00 

Manual  of  Geology.  By  J.  D.  Dana 5.00 

Open  Air  Studies  in  Geology.  By  G.  A.  J.  Cole 3.00 

Ore  De  osits,  By  J.  A.  Phillips 7.00 

Ore  Deposits  of  the  United  States.  By  J.  F.  Kemp 4.00 

Ore  Deposits,  Formation  of  Eruptive.  By  I.  H.  L.  Vogt.  In  Vol.  IV. 

of  "The  Mineral  Industry11 5.00 

Origin  of  Ores,  Views  Held  To-day.  By  J.  F.  Kemp.  In  Vol.  IV.  of 

"  The  Mineral  Industry  " 5.00 

Railway  Guide,  An  American  Geological.  By  J.  Macfarlane 2.50 

Rocks  and  Soils.  By  H.  E.  Stockbridge 2.50 

METALLURGY  -GENERAL. 

Aluminum.    By  J.  W.  Richards 6.00 

Alloys.    Translated  and  edited  by  Wm.  Brannt 4.50 

Alloys  and  Their  Constituents.     By  R.  H.  Thurston 2.50 

Argentiferous  Lead  Ores,  Treatment  of.    By  H.  O.  Hofman.    Articles 
on  this  subject  are  contained  in  Vols.  L,  II.,  III.,  IV.  and  V.  of  "  The 

Mineral  Industry  "  each 5.00 

Copper  Smelting,  Modern.    By  Edward  D.  Peters,  Jr 5.00 

Copper  Sulphate  Manufacture  at  Freiberg.     By  A.  Doerr.    In  Vol.  V. 

of  "  The  Mineral  Industry  " 5.00 

Electro-Chemistry  and  Electro-Metallurgy  in  1896.    By  W.  Borchers. 

In  Vol.  V.  of  "  The  Mineral  Industry." 5.00 

Electro-Chemistry  and  Electro-Metallurgy,   Progress  in   1895.    By  W. 

Borchers.    In  Vol.  IV.  of  "  The  Mineral  Industry  " 5.00 

Electro-Metallurgy.    By  A.  Watt 1.00 

Electro-Metallurgy.     By  G.  Gore 2.00 

Electro-Metallurgy.     By  W.  G.  McMillan 3.50 

Lead  and  Copper  Smelting  and  Copper  Converting.    By  H   W.  Hixon. .  3.00 
Lead,  Metallurgy  of,  and  the  Desilverization  of  Base  Bullion.    By  H.  O. 

Hofman 6.00 

Lead  Burning.    By  J,    E.  Rothwell.    In  Vol.  IV.  of  "  The  Mineral  In- 
dustry " 5.00 

Matte  Smelting.    By  H.  Lang 2.00 

Metals,  Their  Properties  and  Treatment.    By  C.  L.  Bloxam  and  A.  K. 

Huntington 2.00 

Metalliferous  Minerals  and  Mining.    By  D.  C.  Davies 5.00 

Metallurgy  of  Tin.   By  H.  Louis.   In  Vol.  V.  of  "  The  Mineral  Industry.1'  5.00 

Metallurgy,  Introduction  to  the  Study  of.    By  W.  C.  Roberts- Austen. . .  5.00 

Metallurgy,  Elementary.    By  A.  H.  Hiorns 1.00 

Metallurgy,  Elements  of.    By  J.  A.  Phillips 9.00 

Metallurgy  and  Assaying.    By  A.  H.  Hiorns 1.50 

Mill  Practice  in  California.    By  E.  E.  Preston 1.00 

Progress  in  Ore  Dressing  in  1896.    By  R.  H.  Richards.    In  Vol.  V.  of 

"  The  Mineral  Industry  " 5.00 

Rare  Elements.    By  L.   M.  Dennis.    In  Vol.  V.  of  "The  Mineral  In- 
dustry <)1 5.00 

Recent  Improvements  in  Lead  Metallurgy.    By  H.  O.  Hofman.    In  Vol. 

V.  of  "  The  Mineral  Industry  V 5.00 

Regenerator  Furnaces.    By  M.  Graham 1.25 

Zinc  and  Cadmium.    By  W.  R.  Ingalls.    In  Vol.  V.  of  "The  Mineral 

Industry.11 5.00 

Zinc  Refining.    By  Bruno  KerL  In  Vol.  V.  of  "  The  Mineral  Industry. ".  5.00 


GOOD  BOOKS  OF  REFERENCE.  341 

METALLURGY -GOLD  AND  SILVER. 
Amalgamation  of  Free-Milling  Gold  Ores.    By  L.  Janin,  Jr.    In  Vol. 

III.  of  "  The  Mineral  Industry.11 5.00 

Barrel  Chlorination  Process.    By  J.  E.  Rothwell.    In  Vol.  V.  of  "The 

Mineral  Industry  " 5.00 

Chloridizing  Roasting  of  Calcareous  Silver  Ore  Containing  Arsenic  in 
Large  Quantities.    By  O.  Hofmann.    In  Vol.   V.   of  "The  Mineral 

Industry.11 , 5.00 

Cyanide  Process.    By  L.  Janin,  Jr.  In  Vol.  I.  of  the  Mineral  Industry.11  2.50 

Cyanide  Process.    By  A.  Scheidel 1.00 

Cyanide  Process.    By  J.  Parks 2.75 

Cyanide  Process.    By  E.  B.  Wilson 1.50 

.Cyanide  Solutions,  Precipitation  of  Gold  from.     By  W.  R,  Ingalls.    In 

Vol.  IV.  of  "  The  Mineral  Industry.11 , .  5.00 

Getting  Gold.    By  J.  C.  F.  Johnson 1.50 

Gold  Amalgamation,  Losses  in.    By  W.  McDermott  and  P.  W.  Duffield.  2.00 

Gold  and  Silver  Ores.    By  Win.  Hamilton  Merritt 75 

Gold  Chlorination.    By  J.  E.  Rothwell.    In  Vol.  I.  of  "  The  Mineral  In- 
dustry.11   2.50 

Gold  Extraction  at  the  Witwatesrand.    By  W.  R.  Feldtman . , 1.96 

Gold,  Metallurgy  of.    By  M.  Eissler 5.00 

Gold,  Metallurgy  of.    By  T.  Kirk  Rose 6.50 

Gold  Milling.    By  H.  Louis 3.25 

Gold  Mines  of  the  Rand.    By  F.  H.  Hatch  and  J.  A.  Chalmers 5.50 

Gold  Ores,  Notes  on  the  Treatment  of.    By  F.  O'Driscoll 2.00 

Hydro-Metallurgy  of  the  Precious  Metals.    By  Henry  Wurtz.    In  Vol. 

V.  of  "  The  Mineral  Industry  " 5.00 

Leaching  of  Gold  and  Silver  Ores.    By  C.  H.  Aaron 5.00 

Lixiviation  of  Silver  Ores.    By  C.  A.  Stetefeldt 5.00 

Ore  Roasting.     By  Kustel 3.00 

Parting  and  Refining  Gold  and  Silver  Ores.    By  T.  Ulke.    In  Vol.  IV. 

of  •*  The  Mineral  Industry.11 5.00 

Silver,  Metallurgy  or.    By  M.  Eissler 4.00 

South  Africa,  Diamonds  and  Gold  in.    By  T.  Reunert 3.0* 

Stamp  Milling  of  Gold  Ores.    By  T.  A.  Rickard 2.50 

Yukon  Gold  Fields,  Guide  to.    By  V.  Wilson 75 

MINERALOGY. 

Blowpipe  Analysis  and  Determinative  Mineralogy.    By  F.  M.  Endlich. .  4.00 

.blowpipe  Analysis.    By  J.  Landauer 1.00 

Blowpipe  in  Chemistry,  Mineralogy  and  Geology.    By  W.  A.  Ross 2.00 

Determination  of  Rock- Forming  Minerals.    By  E.  Hussack 2.00 

Determinative  Mineralogy.    By  C.  G.  Wheeler , 1.00 

Gems  and  Precious  Stones  of  North  America.    By  G.  F.  Kunz 10.00 

Hand  Book  of  Rocks,  for  Use  Without  the  Microscope.  By  J.  F.  Kemp.  1.50 

Mineralogy.    By  F.  H.  Hatch 90 

Mineralogy  and  Petrography.     By  J.  D.  Dana 2.00 

Mineralogy,  Crystallography  and  Blowpipe  Analysis.    By  A.  J.  Moses 

and  C.  L.  Parsons 2.00 

Mineral' gy,  Descriptive,    By  H.  Bauerman 2.00 

Mineralogy,  Determinative.    By  G.  J.  Brush. 3.50 

Mineralogy,  Elements  of.     By  J.  Nicol 2.00 

Mineralogy,  Handbook  of.    By  J.  C.  Foye 50 

Mineralogy,  New  System  of.    By  J.  D.  Dana 12.50 

Mineralogy,  Systematic.     By  T.  S.  Hunt. 5.00 

Mineralogy,  Text-Book  of.    By  E.  S.  Dana 3.50 

Minerals,  Catalogue  of  American  Localities  of.    By  E.  S.  Dana 1.00 

Minerals,  Catalogue  of,  and  Synonyms.     By  Thos.  Egleston 2.50 

Minerals,  Dictionary  of  Names  of.     By  A.  H.  Chester. ,  3.50 

Minerals,  How  to  Study  Them.    By  E.  S..  Dana. 1.50 


342        PROSPECTING  AND  VALUING  MINES. 

Petrology,  A  Text-Book  of.    By  F.  H.  Hatch 90 

Tables  for  the  Determination  of  Common  Minerals.    By  W.  O.  Crosby..  1.25 

Tables  for  the  Determination  of  Minerals.    By  P.  Frazer ,  1.50 

MINING. 

Accidents,  Mining,  and  their  Prevention.    By  Sir  F.  A.  Abel 4.00 

American  Mining  Code.    By  H.  N.  Copp 50 

Anthrar  ite  Coal  Trade.  Evolution  of.    By  R.  P.  Rothwell.    In  Vol.  IV. 

of  "  The  Mineral  Industry.'1 5.00 

British  Columbia  Mining  Laws 25 

British  Columbia,  United  States  and  Washington  Mining  Laws 50 

Coal  and  Metal  Miner's  Pocket  Book 2.75 

Coal  Mining.    By  H.  W.  Hughes 6.00 

Coal  Mining.    By  George  G.  Andre 15.00 

Coal  and  Coal  Mining.    By  W.  W.  Smyth 1.60 

Colliery  Manager's  Calculator.     By  W.  Fairley 1.60 

Colliery  Manager's  Handbook.    By  C.  Pamely 8.75 

Colliery  Working  and  Management.    By  H.  F.  Bulman  and  R.  A.  S. 

Redmayne 6.00 

Conversation  on  Mines.  Between  Father  and  Son.    By  Wm.  Hopton. . . .  1.25 

Earthy  and  Other  Minerals  and  Mining.     By  D.  C.  Davies 5.00 

Economic  Mining.     By  C   G.  W.  Lock 5.00 

Hydraulic  Mining.    By  A.  J.  Bowie 5.00 

Hydraulic  Mining.    By  T.  E.  Van  Wagenan 1.00 

Lead  and  Zinc  Mining  Industry  of  Missouri  and  Kansas.    By  J.  R.  Holi- 

baugh 50 

Metalliferous  Mines.  Machinery.    By  E.  H.  Davies 5.00 

Mine  Drainage,  Pumps,  Etc.    By  Hans  Behr 1.50 

Mine  Timbering 1.00 

Mine  Ventilation.    By  E.  B.  Wilson 1.25 

Mineral  Industry,  The.    Its  Statistics,   Technology  and  Trade  in  the 
United  States  and  other  countries  from  the  earliest  times.    Vol.  I. 

Statistics  to  the  end  of  1892 2.50 

Vol.  II.    Statististics  to  the  end  of ,1893. , 5.00 

Vol.  III.                 "  1894 5.00 

Vol.  IV.     "             "  1895 5.00 

Vol.  V.                   "  1896 5.00 

Vol.  VI.     "            "  1897 5.00 

Vol.  VII.    "            "  1898 5.00 

Mineral  Lands.    By  H.  N.  Copp 4.00 

Minerals,  Mines  and  Mining.    By  H.  S.  Osborn 4.50 

Miners1  Handbook.     By  John  Milne 3.00 

Miner's  Pocket  Book.    By  G.  W.  Lock 5.00 

Miner's  Pocket  Book.    By  F.  D.  Powers. 3.50 

Mines  and  Mining  Men  of  Colorado 2.50 

Mining.     By  Arnold  Lupton 3.00 

Mining  Engineering.    By  G.  C.  Greenwell. 6.00 

Mining  Laws  of  Colombia ., 1.50 

Mining  Manual  for  1896.    By  W.  R.  Skinner 5.00 

Mining  Rights  in  the  Western  States  and  Territories.  By  R.  S.  Morrison.  3.00 

Mixed  Metals  or  Metallic  Alloys.    By  A.  H.  Hiorns.    Illustrated 1 .50 

Modern  Coke  Ovens  and  By-Products.     By  G.   Lunge.    In  Vol.  V.  of 

"  The  Mineral  Industry.11 5.00 

Ore  and  Stone  Mining.    By  C.  Le  Neve  Foster 10.00 

Phosphates  of  America.    By  F.  Wyatt 4.00 

Practical  Notes  on  Hydraulic  Mining.    By  George  H.  Evans. 1.00 

Practical  Mining.    By  J.  G.  Murphy. 1.50 

Prospecting  for  Gold  and  Silver.    By  G.  Lake 1.00 

Prospectors,  Explorers  and  Miners,  A  Practical  Guide  for.    By  C.  W. 

Moore 4.75 

Prospector's  Field  Book  and  Guide.   By  H.  S.  Osborn 1.50 


GOOD  BOOKS  OF  REFERENCE.  343 

Prospector's  Han •] book.    By  J.  W .  Anderson 1.50 

Prospector's  Manual.    By  H.  N.  Copp 50 

Report  Book  for  Mining  Engineers.     By  A.  G.  Charleton 2.00 

Slate  and  Slate  Quarrying.    By  D.  C.  Dayies 2.00 

Story  of  American  Coals.    By  Win.  J.  Nicolls 3.50 

Story  of  a  Piece  of  Coal.    By  E.  A.  Martin 40 

Story  of  the  Mine  as  Illustrated  by  the  Great  Comstock  Lode.     By  C. 

H.  Shinn 1.50 

Tin  Mining.    By  A.  G.  Charleton 4.25 

Tunneling.    By  H.  S.  Drinker 25.00 

Tunneling.    By  D.  K.  Clark . . 12.00 

Ventilation  of  "Mines.    By  J.  T.  Beard , 2.50 

MISCELLANY. 

Civil  Engineer's  Pocket  Book.    By  J.  C,  Trau twine. 5.00 

Field  Book  for  Engineers.     By  Henck 2.50 

Hydraulic  Formulae.    By  T.  W.  Stone 2.40 

Hydraulic  and  Water  Supply  Engineering.    By  J.  T.  Fanning. 5.00 

Hydraulics,  Practical.    By  P.  M.  Randall , 2.00 

Hydraulics,  Practical.    By  T.  Box 2.00 

Mechanical  Engineer's  Pocket  Book.    By  Wm.  Kent 5.00 

Petroleum.    By  W.  T.  Brannt ..  7.50 

Petroleum.    By  Beuj.  Crew 7.50 

Petroleum  Distillation  and  Modes  of  Testing  Hydrocarbons.    By  A.  N. 

Leet 2.00 

SURVEYING. 

Colliery  Surveying.    By  T.  A.  O'Donohue 50 

Logarithm  Tables.    By  Webster  Wells , 60 

Logarithmic  Tables.    By  Von  Vega : 2.50 

Mathematical  Tables.    By  J.  Pryde 1.75 

Mine  Surveying.    By  B.  H.  Broiigh 2.50 

Plane  Surveying.    By  W.  J.  Raymond 3.00 

Quantity  Surveying  for  Engineers,  etc.     By  J .  Leaning 6..00 

Survey  Practice.    By  L.  D.  Jackson 5.00 

Surveying.    By  W.  M.  Gillespie 2.50 

Surveying.    A  Practical  Treatise  on.   By  H.  S.  Merritt  5.00 

Surveying  and  Levelling  Instruments.    By  W.  F.  Stanley 3.00 

Surveying  Instruments  for  Engineers.    By  I.  O.  Baker 3.00 

Surveying,  Manual  of.    By  F.  Hodgman 2.50 

Surveying,  Practical.    By  G.  W.  Usill,. . ., 3.00 

Surveying,  Theory  and  Practice  of.    By  J.  B.  Johnson 4.00 

Surveyors'  Formulae,  Tables  and  Memoranda.    By  J.  T.  Hur  t 2.00 

Surveyor's  Guide.    By  A.  Duncan 1.50 

Surveyors,  Hand  Book  for.    By  M.  Merriman  and  J.  P.  Brooks 2.00 

Subterraneous  Surveying.    By  T.  Fenwick  and  T.  Baker.  ..,*.., 1.25 


PLATE    1. 

1. — Idealized  step  faults. 

Fig.  2. — Actual  fault  in  the  Leadville  district, 
Fig.  3. — Simple  fissure  without  displacement. 
Fig.  4. — Idealized  fault,  hanging  wall  depressed. 
Fig.  5. — Idealized    fault,     reversed,     foot     wall    de 

pressed. 
FigSo  6,  7, — Actual  condition    of   examples   4  and  5, 

showing  bent  edges  of  the  strata. 
Fig   80 — Contact  vein,  due  to  movement  of  strata 


344 


Plate  1 


•Fig.l. 


2.  Cross  Section  of  ZeadvzIIe  jDistricf 

West  East 

/ron  ///// 

LeadvJ71e 


Quartz/te  MM  Wfi/'te  L/meHi^B/ae  Lime 


PLATE  2. 

Fig.  1. — Illustrating  terms  used  in  describing  rocks. 
A9  conformable  series;  B,  unconformable 
with  A\  C,  D9  E,  unconformable  with  A 
and  B,  but  conformable  among  them- 
selves. 

Fig.  2. — Generalized  structure  of  the  Gomstock  lode. 

Fig.  3. — Difference  between  shales  (a)  and  schists  (b). 

Figs.  4.  5. — Effect  of  pressure  on  the  earth's  crust, 
both  upward  and  downward. 

Fig.  6. — Faults  and  throws  in  veins. 

Figs.  7,  8,  9. — Cross  section  of  the  Cumberland  coal 
mine,  Skagit  County,  Wash.,  showing 
parallelism  of  coal  and  iron  ore  beds. 


346 


PLATE  & 

Figs.  1,  2,    3. — Illustrations  of  trough  faults. 
Fig.  4. — Different  forms  of  fissures,  shown  horizon- 
tally. 
Fig.  5. — Anticlinal  axis  (A)  and  synclinal  axis  (B). 


348 


Plated  Fig.  I. 


Fig.4. 


LO 

CJ) 


PLATE  4. 

Fig.  1. — Folding    of     rocks;    horizontal   plan    (after 

Geikie). 
Figs.  2,  3. — Cross  section   of  the  same    rocks    (after 

Geikie). 
Fig.  4. — Value  of  rock    exposures  to  the  prospector; 

showing  utility  of  surface  croppings,  as 

compared  with  underground  workings. 
Fig.  5. — Trough  faults  in  coal  seam  (after  Jukes). 
Fig.  6. — Extreme  folding  of  strata  by  lateral  pressure 


• 


350 


Plate  4 


Fig.3. 


Fig.4. 


PLATE  5. 

Figs.  1,  2,  3,  4. — Lavas  injected    into    the    bedding 

of  rocks  (after  GeikieV 

Fig.  5. — Granite   intruded  into   metamorphic  schists. 
Fig.  6. — Basalt  intruded  into  coal  seam. 


352 


PLATE  6. 

Fig.  1. — Compression  veins  in  slates  or  shales  (Key- 
stone mine,  Amador  County,  CaL). 

Fig.  2.* — Vein  in  granite,  with  spurs. 

Fig.  3. — Vein  on  contact  of  porphyry  dike;  one 
wall  "frozen." 

Fig.  4. — Vein  on  contact  of  porphyry  dike,  through 
limestone. 

Fig.  5. — Exaggerated  representation  of  "pocket 
mines"  in  granite. 

Fig.  6.— Eefilling  of  a  lode. 

Fig.  7. — Fissure  veins,  with  associated  beds,  at 
Tombstone,  Ariz. 

Fig.  8. — Mineral  deposit  following  joints  in  lime- 
stone. 


354 


Fig.  I.      Plate 


Fig.3. 


Fig  .4 


Fig.  5. 


Fig.6. 


Fig.  7. 


PLATE  7. 

Fig.  1. — Cross  section  of  the  Wheal  Dolcoath,   Corn-. 

wall  (after  C.  Le  Neve  Foster). 
Fig,  2. — Hematite     deposit,      Ulverstone,      England 

(after  C.  Le  Neve  Foster). 

Fig.  3. — Zinc  (calamine)     deposit,    Altenberg,     Ger- 
many (after  C.  Le  Neve  Foster). 
Fig.  4. — "Wheal   Mary   Ann,     Cornwall   (after  C.    Le 

Neve  Foster). 
Fig.  5. — Great     Flat      lode     (England),    segregated 

deposit  (after  C.  Le  Neve  Foster). 
Fig.  6. — Cross  section   of  Mother  lode    in    Mariposa 

County,  Cal. 

Fig.  7. — Bedded  porphyry  and  quartz  veins. 
Fig.  8. — Veins  of  satin  spar  in  conglomerates,  Death 

Valley,  Cal. 
Fig.  9. — Veins  of   quartz     in     conglomerates,   Death 

Valley,  Cal. 
Figs.  10,  11. — Bedded  veins,  cropping  around  hill. 


356 


PLATE  8. 

Longitudinal   section    of    Wbeal    Dolcoath   tin 
Cornwall  (after  C.  Le  Neve  Foster). 


358 


PLATE  9. 

Fig.  1. — Dip  of  veins. 

Figs.  2,  4. — Locating  working  shafts  on  a  lode. 

Figs.  3,  5. — Illustrating  course  of  an  outcrop  in  a  hilly 
country. 

Fig.  6, — Bavine  formed  on  lode,  when  the  ore  con- 
sists of  soft  material. 

Fig.  7. — Eake  of  ore  shoots,  and  formation  of  ravines 
across  a  lode  of  hard  quartz. 


360 


/? 


C  £> 


I 

D  \ 


B    /I 


Fig  6. 


Fig  7. 


PLATE  10. 

Figs.    1,   2,   3.— Formation    of    the    ancient    buried 

gold-bearing  river  deposits  in  California. 
Fig.  4.— Probable      length    of    tunnel      to     tap    the 

"channel." 
Fig.  5.— Side     ravine     or     so-called     "overflow"    of 

gold-bearing  gravel. 
Fig.  6.— Basalt    cone    (6),    through    gravel    bed    (d)3 

at  Laporte,  Cal 


362 


Fig.!, 


Plate  JO ' 


Fig:  2. 


Fig. 3. 


Fig.  4. 


Fig.5, 


Fig. 6. 


PLATE  11. 

Fig.  1. — Showing    present    shape  and    condition    of 

the   ancient    California   river    channels; 

horizontal  plan. 
Fig.  2. — Cross   section  of  Breece    &    Wheeler   placer 

mine,  California. 
Fig.  3. — Petrified     tree,     coated    with     iron    pyrite, 

Sailor  Flat,  Cal. 

Fig.  4. — Fault  in  placer  beds,  Grass  Flat,  Cal. 
Fig.  5. — Eeverse      throw  of   placer     beds,     Laporte, 

Cal. 
Fig.  6. — Faults  in  gravel  bed,  caused  by  dikes. 


364 


Fig.  2 


Fig.3- 


Fig. 4 


Fig.5 


Fig. 6 

C 


PLATE  12. 

Figs.  1,  2. — Folding     of     gravel    beds     at    Tacoma, 

Wash. 
Fig.  3. — Section    of    river    bed,    showing    effect    of 

the  bed  rock  on  the  retention  of  gold. 
Fig.  4. — Slate   quarry,    showing    stratification  lines, 

By  B,  and  cleavage  lines,  L,  L. 
Fig.  5. — Contact  vein,  Garibaldi  mine,  Cal. 
Fig.  6. — Unconformable  gravel  beds,  divided  by  a  bed 

of  sinter. 
Fig.  7. — Changes    of  currents  of   water   in    a   gravel 

deposit,  with  petrified  trees,  Sailor  Flat 

mine,  Cal. 

Fig.  8. — Folding  of  slates  by  pressure   of   dike  (D). 
Fig.  9. — Canon  or   ravine,     following    fault,     Death 
Valley,  Cal. 


866 


Fig.2 


Fig.  3. 


Bed  of 


Fig, 6 


Fig,  7 


Fig.  9 


PLATE  13. 

Figs.  1,  2,  3,  4,  5,  6,  7. —Data   for   estimating   quan- 
tity of  ore  in  a  mine. 
Fig.  8. — Miner's  born  spoon. 
Fig.  9. — Development  of  mines. 
Figs.  10,  11,  12,  13.— Strike  and  dip  of  outcrop. 
Fig.  14. — Mica  crystal, 
Fig.  15. — Hornblende  crystal. 
Fig.  160— Augite  crystal. 


368 


PLATE  14. 

Figs,  1,  2,  3,  4,  5,  6,  7.  — Showing  method  of  mak- 
ing locations,  good  and  bad. 

Fig.  8. — Artesian  well  in  basin  with  continuous  rim 
higher  than  pipe  outlet;  c,  b,  d,  clay 
beds;  g  and  e,  gravel  beds;  a,  surface 
dirt;  w,  well. 

Fig.  9. — Artesian  well  in  basin  with  rim  defective 
on  one  side;  but  which  flows  because  the 
basin  is  sealed  by  the  water-tight  clay 
bed  c;  g,  gravel  bed;  a  and  b}  clay  seams; 
w,  well. 


370 


Fig.5 


PLATE   15. 

Figs.  1,  2. — Correct  form  of  blaze  on  trees  as  witness 

marks.     Fig.   1,   front  view;  fig.  2,  side 

view. 
Figs.  3,  4. — Good   (3)   and    bad    (4)    stone-and-stake 

monuments. 

Fig.  5. — Posting  location  notice  in  tin  can. 
Figs.  6-12. — Making  locations  (see  Chap.  X.), 
Figs.  13,  14. — Blind    lodes;    longitudinal   and   cross 

sections. 


378 


Fig.5. 


Fig. I.       Fig  2          Fig  5. 


ff.q.S.  Del?. 


INDEX. 


Abyssinia,  Erosion  in 159 

Adamantine 207 

Agricultural  rights 172 

Alabaster 48 

Alston  Moor  mine 101 

Altenberg  mines 116 

Amador  mines 102 

Amorphous. . . » . .  . . . 207 

Anglesite 216 

Annabergite 224 

Anthracite 262 

Anticlines 146 

Antimonial  silver 210 

Antimonides  and  arsenides 132 

Antimony  and  country  rocks....  128 

Antimony  ores 226 

Apatite 39 

Aqueous  theory 106 

Arastra 28 

Arborescent 207 

Area  vein  worked 33 

Argentite 210 

Arsenic 226 

Arsenical  pyrite 221 

Arsenides  and  antimonides 132 

Artesian  wells 310,  315 

Asbestos 229 

Asbestos  in  hornblende  rocks 164 

Asphaltum 231 

Assaying 24 

Assessment  work 171 

Atacamite 215 

Atomic  weight 316 

Attle 205 

Augite 39 

Autunite 228 

Azurite 214 

B 

Backs 34 

Bald  Mountain 134 

Bars,  River 298 

Barytes 229,  231 

Basalt 51,  54,    58 

Basalt,  Prospecting  in 164 

Batopilas .6,  101,  103 

Bauxite 232 

Becker,    G.     F.,    on    Steamboat 

Springs 107 

Bedding  planes 41 

Bedrock 275,  287 

Beds,  Dip  of 146 


Beds,  Ore .................  144 

Beds,  Outcrops  of 147 

Beds,  Thickness  of 69 

Beds,  Workable 71 

Bendigo  mines 133 

Bibliography 338 

Bismuth,  Native 226 

Bismuth  ores 226 

Bituminous  coal 263 

Black  silver , 211 

Blende 218 

Blende  and  galena.  Separating....    26 

Blind  lodes....... 77 

Bog  iron  ore 8,  143 

Books  of  reference 338 

Borate  of  lime 251 

Borax 142,  251 

Borehole  records 315 

Borehole,  Sperenberg 141 

Borings  for  coa^ 10 

Borings  in  gravel 10 

Borings,  Useless 8 

Bornite 213 

Botryoidal 207 

Bottom  gravel 275 

Bowlder  clay 67 

Breccia 66 

Breece  &  Wheeler  mine 277 

Brick  clays 243 

Brilliant 207 

Brittle 207 

Brittle  silver 211 

Bromide  of  silver 116,  211 

Buhrstones 61 

Bulk  of  ores 18 

Burchardite 213 


C.  &C.  shaft 109 

Cadmium 227 

Calamine 217 

Calaverite . .  210 

Calico  district. . . . , 105 

Cannel  coal 265 

Canon  Creek 158 

Cap  rock 278 

Carbonate  of  copper 214 

Carbonate  of  lead 216 

Carbonate  of  zinc 217 

Carmen  island  salt. 141 

Carpenter    F,  B.,  on  Dakota  gold 

mines 134 

Cascade  range 136 


INDEX. 


375 


Caspian  sea  salt . . . ,  —  141 

Caves 148 

Caving 13 

Celestite , 247 

Cerargyrite 211 

Cerussite 216 

Chalcocite 213,  215 

Chalcopvrite 212 

Chalk..: 45 

Charges  for  locations 191 

Cheshire  salt 141 

Chile  saltpeter 255 

Chloride  of  copper „ 215 

Chloride  of  silver 116,  211 

Chlorite 89 

Chlorite  schists 65 

Chrome  and  country  rocks 128 

Chrome  in  schists 102 

Chrome  occurrences 132 

Chrome  ores. 223 

Chromite 223 

Chry  socolla 215 

Chrysolite 39 

Chutes 81,  204 

Cinnabar 11,  212 

Claims  (See  also  Locations). 

Claims,  Locating 167 

Clay  analyse^ 243 

Clay,  Bowlder 67 

Clay,  Brick 243 

Clay,  Fire 234 

Clay  gouge 79 

Clay,  Mine 14 

Clays 62 

Cleat 263 

Cleavage 40,  330 

Coal..... 259 

Coal  beds,  Faulted 9 

Coal,  Commercial  value 269 

Coal,  Composition  of 260 

Coal,  Impurities  in 266 

Coal  mines,  Creeping 1C 

Coal  prospecting 269 

Cobalt  bloom 2^5 

Cobalt  in  ocean 107 

Cobalt-nickel 132 

Cobalt  ores 225 

Cobaltite. .  , 225 

Coke  tests 268 

Colombia,  Sulphur  in 248 

Compact 207 

Compass 165 

Competition 10 

Compression  veins 93,  102 

Conistock  lode. . .  .13,  20.  78.  92,  95,  101 
107,  109,  111,  112,  113 

Concentration 30 

Conchoidal 207 

Concretionary 207 

Conditions,  Favorable 19 

Conglomerate,  Volcanic 66 

Conglomerates 60 

Contact  veins 91 

Contacts,  Limestone , 94 


Contests,  Location 195 

Copper  and  country  rocks 126 

Copper  chloride 215 

Copper  in  beds 144 

Copper  mines,  Lake 100 

Copper,  Native 212 

Copper  occurrences 131 

Copper  ore,  Testing. 27 

Copper  ores 212 

Copper  oxide , 214 

Copper-silver 100,  13^ 

Copper  sulphate 213 

Copper  surface  ores 160 

Coralline  limestone 46 

Cornish  mines 103,  104,  110,  112 

Corundum 236 

Country  rock  and  gangue 133 

Country  rock  samples 155 

Country  rocks  and  vein  filling 120 

Country  roc  us,  Effect  on  fissures.     90 

Cracow  salt —  141 

Creeping .' 13 

Croppings 72 

Cross-cutting 202 

Cross-cut  tunnels 197 

Cryolite 236 

Crystal 246 

Crystallization  of  minerals 320 

Cubanite 213 

Curtis,  J.  S.,  on  gold  and  silver  in 

rocks 107 

Cuprite 213 


Dacite 55 

Daintree  on  gold  occurrences 107 

Dana  on    metals  in    gneiss    and 

granite 107 

Dana  on  nickel  in  lava 107 

Daubree  on  meteoroids 108 

Death  Valley 88,  101 

Decomposition  of  ore  at  surface. .  160 

Deep  gravels 276 

Deposits,  Evaporated 143 

Deposits,  Form  of 112 

Deposits  in  limestone 103,  115 

Deposits,  Mineral  sediment 143 

Deposits  other  than  veins 138 

Deposits,  Physical  character  of. . .     69 

Depth,  Richness  in 159 

Derbyshire  mines 135 

Development 4,  197,  203 

Diatomaceous  earth 48,  240 

Dikes 72,76,    99 

Dikes,  Lodes  on 94,  154 

Diorite,  Gold  in 107 

Dip 70,  73,  146 

Discharge  of  water 304 

Dolcoath  mine 13 

Dolomite 47 

Dredging 299 

Drift  mining 291 

Drift  tunnels 200 

Drifts «, , 804 


376 


INDEX. 


Dry bone 

Dry  washing. 
Ductile  , 


217 

297 

207 

E 

Electro-chemical  action 117 

Elements 316 

Elevator,  Hydraulic 297 

Elvanite 53 

Embolite 211 

Emerald  nickel 224 

Emery 236 

End  lines 183 

Epsom  salt 142 

Erosion  of  veins 159 

Erythrite 225 

Evaporation 139 

F 

Faults 83 

Faults  in  gravels 282 

Faults,  Reverse 85 

Faults,  Step 86 

Faults,  Strike 90 

Faults,  Trough 87 

Feel  of  minerals 330 

Feldspar 37 

Felsite 53 

Fibrous 207 

Filiform 207 

Filling  of  veins , 99 

Fire  clay 62,  234 

"  Fissure  veins,  True11 89 

Fissures 83 

Flagstones.  : 61 

Flaming  coal. 264 

Flint 46 

Float , 162 

Floor 69 

Fluorspar 237 

Folded  gravels 283 

Foliated 207 

Foot  wall  tunnels 199 

Forchhammer   on  metals  in  sea 

water 106 

Formations,  Succession  of 138 

Forms  of  minerals 321 

Fragmental  rocks 66 

Franklinite 218 

Eraser  river 298 

Freestone 61 

Frieslebenite 211 

Frozen  veins 80 

Fuliginous  coal 264 

Furnace  Creek 104 

Fusibility  of  minerals 322 

G 

Galena 215 

Galena  and  blende,  Separating. . .  26 

Galena  in  limestone 102,  164 

Gangue 80 

Gangue  and  country  rock 133 

Garibaldi  mine 7 

Garnets 39 


Gas  coal. . ............  3 .....  o .....  264 

Gas,  Natural 258 

Gash  veins 86,    95 

Geikie  on  salt  in  Caspian 141 

Genthite........ 224 

Geodes 102 

Geologic  series. 67,  322,  323 

Geological  Survey,  U.  S 68 

Georgia  mines 136 

Gersdorffite... 224 

Glacial  depo  its 285 

Glacial  products 67 

Glacier  mine '. 114 

Gneiss 64 

Gneiss  and  granite.  Ores  in 107 

Gob 205 

Gold  and  country  rocks 122 

Gold  and  silver  in  rocks 107 

Gold,  Crystallized 101 

Gold  gravel  deposits 271 

Gold  gravels,  Faults  in 282 

Gold  gravels,  Folds  in 283 

Gold  in  beds 144 

Gold  in  diorite 107 

Gold  in  granite ,  102 

Gold  in  sea  water 106 

'Gold  in  serpentine 107 

Gold  in  South  Dakota 134 

Gold,  Native 209,  259 

Gold  occurrences 131 

Gold  ore.  Assaying 24,    25 

Gold  ore,  Free 12 

Gold  ore,  Horning 25,    26 

Gold  ore,  Testing 25 

Gold  pan 288 

Gold,  Saving  fine 299 

Gold,  Tests  for 296 

Gold  tellurides 209 

Gold  veins,  Erosion  of 159 

Gouge 79 

Grade  of  gravel  deposits 275 

Grade  of  ore 21 

Grand  Canon 159 

Granite 37,    52 

Granite,  gold  in K  2 

Granite,  Veins  in 97 

Granular 207 

Graphite 238 

Gravel  deposits 271 

Gravel  deposits,  Origin  of 272 

Gravel  mines,  Clay  in 14 

Gravel  mines,  Creeping  in 13 

Gravel  mining 286 

Gravel,  Faults  in 282 

Gravel,  Folds  In 283 

Gravel,  Testing 296 

Gray  copper 213 

Great  Flat  lode 112 

Gypsum 14,  48,  143,  239 

Gypsum  in  solution 141 

H 

Hammers,  Geological 166 

Hanging  wall  tunnels. 199 


INDEX. 


37? 


Head  Center  mine 100 

Head  of  water 304 

Heading 204 

Heat,  Underground 109 

Hematite 219 

Hillside  deposits 283 

Horn  silver ,100,  105,  211 

Horn  spoon 25,  165 

Hornblende 39 

Hornblende  rocks,  Asbestos  in 164 

Horses 79,    91 

Hydraulic  elevator. 297 

Hydraulic  mining 289 


Igneous  theory. 
Illinois  mines. . . 


I 


115 

Ilmenite 221 

Inch,  Miner's 302,  309 

Incline 204 

Infusorial  earth 48,  240 

Iridescent 207 

Iridosmine 212 

Iron  carbonate 220 

Iron-manganese 132 

Iron  ore  beds 143 

Iron  ore,  Bog 8,  143 

Iron  ores 219 

Iron  sulphide 220 

Isabel  mine 105 


Joints,  Strike 41 

Jukes  on  trough  faults 87 


Kaolin 62 

Karaboghaz  salt 141 

Keystone  mine 93,  112 

Killas 103 


Lake  Superior  mines 144 

Lakes,  Saline 59 

Lamination 41 

Land  prices 195 

Lands,  Agricultural 172 

Lands,  Timber 172 

Lapilli 66 

Laterals 281 

Lava 50,    51 

Lava  cup 278 

Lava,  Nickel  in 107 

Lead 72 

Lead  and  country  rocks 125 

Lead  and  silver 132 

Lead  carbonate 216 

Lead  in  Derbyshire 135 

Lead  in  limestone 115,  164 

Lead,  Native 215 

Lead  occurrences 131 

Lead  ore .9,  101 

Lead  ore  in  beds 144 

Lead  oxide 216 

Lead  sulphate. 216 


Lead-zinc 182 

Leadville .9,  92,  148 

Ledge 72 

Leeds  mine 105,  144 

Levels 204 

Light  and  minerals 320 

Lime  sulphate 239 

Limestone .45,  241 

Limestone,  Caves  in 148 

Limestone  contacts , 94 

Limestone,  Coralline 46 

Limestone,  Deposits  in...  103,  115,  164 

Limestone,  Prospecting  in 164 

Limonite 219 

Litigation 14 

Liversidge  on  gold  in  sea  water. .  107 

Locating  regulations 189 

Location  charges 191 

Location  end  lines 183 

Location,  Final  proof  of 194 

Location  length 183 

Location  notices 175,  176 

Location,  Publication  of 193 

Location  requirements 168 

Locations,  Describing 150 

Locations,  How  made 170,  177 

Locations,  Imperfect 168 

Locations,  Lode 171,  177,  188 

Locations,  Making 167 

Locations,  Placer 170 

Locations,  Procedure  in 191 

Locations,  Puzzling 185 

Lode 72 

Lode  length 183 

Lode  line 179 

Lode  locations 171,  177,  188 

Lode  locations,  Procedure  in 188 

Lodes,  Blind 77 

Lodes  on  dikes 94 

Lost  vein 6 

M 

Machine  washing 295 

Magnesite 47,  242 

Magnet 165 

Magnetite 219 

Malachite 214 

Malleable 207 

Mammillary . . 208 

Mammoth  cave 115,  148 

Manganes^  and  country  lodes....  129 

Manganese  in  ocean 107 

Manganese-iron 132 

Manganese  occurrences 132 

Manganese  ores 221 

Marble ..    47 

Marcasite 220 

Marks,  Stake , 173 

Marks,  Tree 173 

Masses 81 

Massicot . 216 

Massive 208 

Matrix. 80 

Mary  Ann  mine 110,  112 


378 


INDEX. 


Melaconite 214 

Mercury  (See  Quicksilver). 

Metacinnabarite 212 

Metallic  luster 208 

Metallurgical  experiments 3 

Metallurgical  plant,  Planning 29 

Metals  and  rocks 130 

Metals  associated  with  each  other  132 

Metals,  Distribution  of 106 

Metals,  Sp.  gr.  of 17.    18 

Metals,  Value  of .'  331 

Meteoroids 108 

Metamorphic  rocks. .  „ 64 

Metamorphism 42 

Metric  system. 335 

Mica 38,  242 

Micaceous , 208 

Mill  capacity 32,    33 

Mill  runs 27 

Millstones 61 

Mine  cost  and  output 16 

Mine,  Definition  of 34 

Mine  failures,  Causes  of 14 

Mine  water 157,  201 

Mine,  What  constitutes  a 16 

Minerals.  Characters  of 320 

Minerals,  Classification  of 318 

Minerals  Cleavage  of 330 

Minerals,  Crystallization  of 320 

Minerals  distinguished  according 

to  feel 330 

Minerals  distinguished  according 

to  odor 330 

Minerals  distinguished  according 

to  taste 330 

Minerals,  External  Forms  of 321 

Minerals,  Fracture  of 321 

Minerals,  Fusibility  of 322 

Minerals,  Hardness  of 330 

Mineral  "  in  place  " 172 

Minerals,  Insoluble 229 

Minerals,  Qualities  Depending  on 

Light  of 320 

Minerals,  Rock-forming 36 

Minerals,  Separating 26 

Minerals,  Soluble 250 

Minerals,  Structure  of 321 

Minerals,  Useful 229 

Minerals,  Value  of 331 

Minerals,  Worthless 11 

Miner's  inch 302,  309 

Mines,  Development  of 4,  197,  203 

Mines,  Unsuccessful , 10 

Mines,  Working  facilities 157 

Mining  conditions 19 

Mining  Drift 291 

Mining  failures 2,    14 

Mining  ground,  Patents  to 187 

Mining,  Hydraulic . . . . .  289 

Mining,  Mistakes  in 1 

Mining,  Placer 286 

Minium 217 

Mispickel 221,  225 

Molybdenum 227 


Mono  lake 

Monte  Cristo  district 78,  113, 

Monuments 173,  174, 

Mother  lode 76,  104,  119, 

N 


.  ,„       mines 

Nagygite 

Natural  gas 

Niccolite 

Nickel  and  country  rocks. . 

Nickel-cobalt 

Nickel  in  lava. 

Nickel  in  ocean ..., 

Nickel  ocher 

Nickel  ore 

Nickel  silicate  

Niter 

Niter,  Chile 

Niter  (See  Saltpeter). 
Notic"s  of  locations  — 

Notices,  Posting 

Nova  Scotia  schists 


Obsidian 

Ocotilla 

Odor  of  Minerals , 

Opals  in  basalt 

Olivine 

Onion  Valley  dike 

Oolitic 

Opaque 

Ore  change  at  water  level 

Ore,  Definition  of 

Ore  deposits  and  country  rocks. . . 

Ore  deposits,  Form  of , 

Ore,  Distribution  of 

Ore,  Grade  of 

Ore  in  depth 

Ore  in  limestone 103,  115, 

Ore  "in  sight11 

Ore,  Origin  of 

Ore,  Pockety 

Ore  sampling 

Ore,  Solution  of 

Ore,  Source  of 

Ore  supply  needed 

Ore  deposits,  Physical  char,  of ... 

Ore  thickness 

Ore  tonnage 

Ores  arid  rocks 

Ores,  Bulk  of 

Ores  from  sea 

Ores,  Separating.  „ 

Ores,  Sp.  gr.  of 17, 

Ores,  Value  of 

Ores,  Weight  of 

Orpimen  t 

Otago  mines 

Outcrop 

Outcrop  and  springs 

Outcrop  and  vegetation 

Outcrop  in  location 

Outcrop,  Lesson  of  the 7, 


142 
114 
181 
154 

6 
210 
258  . 
224 
128 
,  l&J 
,  107 
,  107 
,  224 
,  224 
.  224 
.  254 
.  255 

,  175 
,  176 
.  133 

.  56 
.  152 
.  330 
.  164 
.  39 
.  99 
.  208 
.  208 
.  159 
206 
122 
112 
12 
21 
159 
164 
21 
106 
6 

23 
109 
111 
31 
69 
153 
32 
130 
18 
116 
26 
18 
331 
19 
226 
133 
72 
153 
152 
179 
158 


INDEX. 


379 


Outcrop  of  veins 74 

Outcrop,  Circular 78 

Outcrop,  Rusty 161 

Outcrops  of  beds 147 

Outfit,  Prospecting 165 

"Overflows,"  Gravel 281 

Oxides  of  iron 219 

Ozokerite 244 


Pan , 2£ 

Panning « 

Patents 1&7 

Patents,  Procedure  in 191 

Petroleum 257 

Petzite 210 

Phosphate  of  uranium 228 

Pick,  Prospecting 166 

Pipe  clay 278 

Pipes,  Water  in 304 

Pisolitic 208 

Pits,  Prospect 2( 

Placer  locations 170 

Placer  mining 286 

Plaster  of  paris 48,  239 

Platinum < 211 

Plumbago 238 

Pockets 6 

Pockets,  Fault 85 

Porcelain  clay 62 

Porphyry 53,  55,    58 

Posting  notices 176 

Potassinm  nitrate 254 

Potter's  clay 243 

Price  and  profits 20 

Prices  of  metals,ores,  minerals,etc.  331 

Promoters 4 

Prospecting 150 

Prospecting  and  springs 15f<5 

Prospecting  and  vegetation 152 

Prospecting  and  water  system —  163 

Prospecting  for  coal 269 

Prospecting  outfit 165 

Prospecting— WThat  to  look  for....  164 

Prospecting— Where? 164 

Prospect  pits 203 

Proustite = 211 

Psilomelane 222 

Publication  of  location 193 

Pumice 243 

Pyrargyrite 210 

Pyrite 220 

Pyrite,  Auriferous 27 

Pyrite,  Decay  of 114,  161 

Py rolusite 222 

Pyrrhotite 221,  224 

Q 

Quartz 37,  243 

Quartz  porphyry 55 

Juarzfte 61 

Quicklime 47 

Quicksilver  and  county  rocks 129 

Quicksilver  at  Steamboat  Springs.  107 
Quicksilver  for  testing 165 


Quicksilver,  Native 212 

Quicksilver  occurrences 132 

R 

Ramsay  on  Bath  salts 139 

Realgar 226 

Reduction  works,  Plan  ing 29 

Reduction  works,  Unsuitable  ....      5 

Regulations  for  locating 189 

Regulations,  Local 171 

Reniform  208 

Reserves 4,  5,    34 

Resinous 208 

Reverse  throws 85 

Rhyolite 35 

Ribbon  rock 95 

Ribbon  structure   110 

Richmond  Con.  mine  4 

Rio  Virgen  salt  141 

River  bars  298 

River  deposits 274 

Roads 29 

Rock  and  gangue 133 

Rock  names  156 

Rock  samples 155 

Rocks 36 

Rocks  and  metals 130 

Rocks,  Ohem.  precipitated 44 

Rocks,  Classification  of . . .  .43, 324,  326 

Rocks,  Composition  of 58 

Rocks,  Compound 49 

Rocks,  Crystalline 50 

Rocks,  Effect  on  fissures 90 

Rocks,  Eruptive  133 

Rocks,  Fragmental 66 

Rocks,  Influence  on  vein  filling. . .  120 

Rocks,  Metam  orphic 64 

Rocks,  Organic  44 

Rocks,  Origin  of 44 

Rocks,  Silicious 131 

Rocks,  Simple   45 

Rocks,  Stratified 57 

Rocks,  Volcanic 66 

Roof 69 

Ruby  Basin 134 

Ruby  silver 210,  211 

Rutile 227. 

s 

Salt 141,  256 

Salt  at  Sperenberg 141 

Salt  in  Arizona 141 

Salt  in  Caspian 141 

Salt  in  Cheshire 141 

Salt  in  Poland 141 

Salt  in  solution 141 

Saltpeter 142,  254 

Saltpeter.  Chile 255 

Saltpeter  prospecting 164 

Salts,  Soluble,  Prospect  ng  for. . .  ie:4 

Samples  country  rock 155 

Sampling 23 

Sandberger  on  metals  in  rocks. . ..  107 

Sandstones , 61 

Satin  spar 101,  239 


380 


INDEX. 


Savage  mine 

Schists 42, 

Sea  beach  deposits 

Sea-formed  ores 

Sea  water.  Metals  in , 

Sediment  mineral  deposits 

Segregated  veins 

Selenite 48, 

Selvage 

Semi-anthracite 

Semi-bituminous 

Serpentine , 

Serpentine,  Gold  in 

Shafts 3,  200, 

Shafts,  Useless 

Shales 

Shoots,  Ore 81, 

Siderite 

Sierra  Nevada  mine 

Silicate  of  nickel 

Silicate  of  zinc 

Silver  and  country  rocks 123, 

Silver  and  gold  in  rocks 

Silver  at  Leeds 105, 

Silver,  Brittle . . . . 

Silver  bromide 116. 

Silver  chloride 116. 

Silver-copper 100, 

Silver  glance 

Silver  in  sea  water 

Silver  in  South  Dakota 

Silver-lead. 

Silver,  Native 101, 

Silver  occurrences 

Sinking. 

Sinter 

Slate 42,  43, 

Slate  Creek 
Slickensides 

Smaltite 

Smelting 

Smithsonite 

Soapstone 

Sodium  carbonate 

Sodium  sulphate 

Solfataric  action 

Solutions,  Mineral 109,  134, 

South  African  mines 

South  Dakota  mines 

Specific  gravity 17, 

Sperenberg  boring 

Spoon 

Springs  and  outcrops 

Spurs 78, 

Stakes 

Stalactitic 

Stamp,  Duty  of 

Stamp  mill  capacity 

Stannite 

Steamboat  Springs 

Step  faults 

Stephanite 

Stibnite 

Stockworks 89, 


113    Stone  monuments 173 

65    Stonewall  Jackson  mine 95,  135 

284    Stoping 204 

116    Stratification 40,    60 

106  Streak  plate 166 

143  Stream  tin 223 

95    Strike 70,    74 

239    Strike  faults 90 

.  79    Strike  joints 41 

262  Strontia 246 

263  Structure  of  minerals 321 

49    Stulls 205 

107  Subconchoidal 258 

201    Submetallic 258 

8    Sulphate  of  copper 215 

63    Sulphate  of  (sad 216 

204    Sulphate  of  soda 256 

220     Sulphide  of  iron 220 

101    Sulphide  of  mercury 212 

224    Sulphide  of  tin ' 223 

217    Sulphide  of  zinc 218 

124    Sulphur 247 

107     Sulphur  Banks 248 

144  Sulphurets,  Panning 166 

211     Sulphurets,  Separating 26,  166 

211     Sump 205 

211    Surface  ores 159,  160,  161 

132    Survey,  Order  for 192 

210    Surveyor,  Authority  of 169 

106  Surveyor,  Duties  of 188,  190 

134    Surveyor's  fees 188 

.  132  Surveyors,  Instructions  to ....  189,  196 

210  Sutro 'tunnel Ill 

131     Slitter  Creek  mines 102 

200    Syenite .......54,    58 

46    Sylvanite 210 

,  63    Synclines 146 

%  T 

f>25    Tables: ...... 316 

29       Elements 316 

217       Geologic  Series 67,  322,  328 

249  Metals,    Ores,    Minerals,     etc., 

253  Value  of 331 

256        Metric  System 335 

111        Minerals,  Characters  of 320 

139       Minerals,  Classification  of 318 

144       Minerals,  Cleavage  of 40,  330 

134       Minerals,  Crystallization  of 320 

18  Minerals  distinguished  accord- 

141  ing  to  feel 330 

25  Minerals  distinguished  accord- 

153  ing  to  odor 330 

84  Minerals  distinguished  accord- 

173  ing  to  taste 330 

258       Minerals,  External  forms  of 321 

32  Minerals,  Fracture  of 321 

33  Minerals,  Fusibility  of 322 

223       Minerals,  Hardness  of 330 

107  Minerals,    Qualities    depending 

86  on  light  of 320 

211  Minerals,  Structure  of 321 

226  Rocks,  Classification  of.. 43,  324.  326 

103    Talc 249 


INDEX.  381 

Talus 77    Veins  not  uniform 12 

Tape .165    Veins  on  dikes ..94,  154 

Taste  of  minerals 330    Veins,  Opening 157 

Tellurides 195,  209    Veins,  Origin  of , .  .83,    96 

Tests,  U  tility  of 28    Veins,  Pockety , 119 

Tests,  Working 27    Veins,  Richness  in  depth 159 

Tetrahedrite 213    Veins,  Segregated 95 

Theory-,  Aqueous 106    Veins,  Thickness  of 69,  153 

Theory,  Igneous 99    Veins,  4k  True  fissure  " 72,    89 

Thickness  of  vein  and  ore 153    Velocity  of  water  discharge 305 

Throw 84,    85    Vesuviau  lava 107 

Timber  rights 172    Vitreous  copper 213 

Time,  Geologic 68    Vitreous  silver 210 

Tin  and  country  rocks 128    Volcanic  products e 66 

Tin  occurrences 131  w 

Tin  ore 11,  222 

Tiusulphide 223    w a? •  •  ••  : 222 

Titanic  iron 221    Was,  False 154 

Titanium  227     "WSj  vein 79 

Tombstone .':.'.'.':.':::.'.".v.'.'.v.Vii6, 157  s*™**? mines 95' 113'  *™ 

Tonnage  area  17    Water,  Bulk  of 302 

Toimaircafcuiationof:;:::::.8i;    32    Water  discharge 304 

Tonotrranhv  163    Water  in  mines 1 57,  201 

To?b!rn1?ey:::.v.v.v:.:.v. :;::;:::  *»  water  level 159 

Tourmaline 39    Water  measurement 306 

Trachyte 53,    58    Water,  Mine 108 

TrAnafiiftpnt  2^    Water  power 305 

TransparentV/.-.V.-.-.-.-.-.-.-.-.-.-: '. '. '. '. '. '.  858    Water  Pref  »re-  • : «* 

Transpr'taf  n  of  mineral  by  water  109  Water  system  and  prospecting. . .  ua 

rrm t">  ^7     **  ater,  u nit  or oO,* 

Tmna'"  "  253    Water,  Weight 302 

Trough  faults'. '. '. '. '. '. '. '. .' .' .' .' .' . .' ." '. .' .' .' .'    87    Waters,  Solvent  power  of 139 

-True  fissure  ve.ns  " 89  WMgj^^.^^.;.,...^.,  958 

TungsVen\\\\\\\'::.v.v::::::::::::  22?  weight  of  ores 19 

Tunnel  connections 199    Weirs     •.••••••• J06 

Tunnels,  Cross-cut 197    West  Point,  Cal. 102 

Tunnels   Drift 200    Whea   Dolcoath 110 

Tunnels  in  foot  or  hanging  wall...  199    Wheal  Mary  Ann 110,  112 

Tyndall  mine '. 78    Wjjjemite ° |$ 

U  Wisconsin  mines 115 

Ulexite 251    Wolfram 227 

Ulverstone  deposits 116    Wood  tin ,  223 

Uranium 228    Working  facilities 157 

y  Works,  Planning , 29 

.    Works,  Unsuitable 5 

Valuation  of  mines 20 

Values  of  metals,  ores,  minerals,  Y 

etc 331  Yale                                                     298 

Vanadium .'••??§  Yankee  Hiti.' .'.'.'.'.'.'.'.'.'.'. '.'.'.'.'. '.'.'.'.'.'.  101 

Vegetation  a  guide  in  prospecting  153    Yellow  Jacket  mine 109 

Vein,  Area  extracted 33    Yucca...  152 

Vein,  Distance  traceable 151  ........ 

Vein  filling 99  *- 

Vein  matter 80    Zinc  and  country  rocks 127 

Vein  structure 6    Zinc  at  Altenberg 116 

Veins,  Blind 77    Zinc  carbonate 217 

Veins,  Compression. 93,  102    Zinc  occurrences 131 

Veins,  Contact 91    Zinc  ores 217 

Veins,  Definition  of 72    Zinc  oxide 218 

Veins,  Frozen 80    Zinc  silicate 217 

Veins  in  granite ". 97    Zincblende 218 

Veins,  Measuring 153    Zincite 218 

Veins,  Narrow 6    Zinc-lead ,  . , , 133 


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